Class 8 Exam  >  Class 8 Notes  >  RD Sharma Solutions for Class 8 Mathematics  >  RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2)

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics PDF Download

Question 1: Find each of the following product:
5x2 × 4x3

Answer 1: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices. However, use of these laws are subject to their applicability in the given expressions.
In the present problem, to perform the multiplication, we can proceed as follows:
5x2×4x3=(5×4)×(x2×x3)5x2×4x3=5×4×x2×x3
=20x5=20x5                           ( am×an=am+nam×an=am+n)
Thus, the answer is 20x520x5. 

Question 2: Find each of the following product:
−3a2 × 4b4

Answer 2: To multiply algebraic expressions, we can use commutative and associative laws along with the law of indices, am×an=am+nam×an=am+n, wherever applicable.
We have:
3a2×4b4=(3×4)×(a2×b4)=12a2b4-3a2×4b4=-3×4×a2×b4=-12a2Thus, the answer is 12a2b4-12a2b4. 

Question 3: Find each of the following product:
(−5xy) × (−3x2yz)

Answer 3: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, am×an=am+nam×an=am+n, wherever applicable.
We have:
(5xy)×(3x2yz)={(5)×(3)}× (x×x2)×(y×y)×z=15× (x1+2)×(y1+1)×z=15x3y2z-5xy×-3x2yz=-5×-3× x×x2×y×y×z=15× x1+2×y1+1×z=15x3y2Thus, the answer is 15x3y2z15x3y2z. 

Question 4: Find each of the following product:

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Answer 4: To multiply algebraic expressions, we use commutative and associative laws along with the the law of indices, that is, am×an=am+nam×an=am+n. 

We have: 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Thus, the answer is 1/6 x3y2z216x3y2z2. 

Question 5: Find each of the following product:

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Answer 5: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n. 

We have: 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics (x×x2)×(y2×y)×(z×z2) 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(x1+2)×(y2+1)×(z1+2) 

= - 91/15 x3y3x3

Thus, the answer is = - 91/15 x3y3x3 

Question 6: Find each of the following product:

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Answer 6: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n. 

We have: 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(x3×x)×(z×z2)×y 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(x3+1)×(z1+2)×y 

9/10 x4yz3=910x4yz3  

Thus, the answer is  9/10 x4yz3=910x4yz3  

Question 7: Find each of the following product:

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Answer 7:To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n.
We have: 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics (a2×a3)×(b2×b2)×c2 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics  (a2+3)×(b2+2)×c2 

= - 1/6 a5b4c2 

Thus, the answer is = - 1/6 a5b4c2

Question 8: Find each of the following product: 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Answer 8: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n.
We have: 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

=(7×1/4)×(x×x2)×(y×y)×z 

=(7×1/4)×(x1+2)×(y1+1)×z 

= 7/4 x3y2z

Thus, the answer is  7/4 x3y2z 

Question 9: Find each of the following product:
(7ab) × (−5ab2c) × (6abc2)

Answer 9: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e.,  am×an=am+nam×an=am+n.
We have: (7ab)×(5ab2c)×(6abc2)={7×(5)×6}×(a×a×a)×(b×b2×b)×(c×c2)={7×(5)×6}×(a1+1+1)×(b1+2+1)×(c1+2)=210a3b4c3 Thus, the answer is 210a3b4c3-210a3b4c3. 

Question 10: Find each of the following product:
(−5a) × (−10a2) × (−2a3)

Answer 10: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n.
We have:
(5a)×(10a2)×(2a3)={(5)×(10)×(2)}×(a×a2×a3)={(5)×(10)×(2)}×(a1+2+3)=100a6
Thus, the answer is 100a6-100a6. 

Question 11: Find each of the following product:
(−4x2) × (−6xy2) × (−3yz2)

Answer 11: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n.
We have:
(4x2)×(6xy2)×(3yz2)={(4)×(6)×(3)}×(x2×x)×(y2×y)×z2={(4)×(6)×(3)}×(x2+1)×(y2+1)×z2=72x3y3z2Thus, the answer is 72x3y3z2-72x3y3z2.

Question 12: Find each of the following product:

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Answer 12: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n.
We have: 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(a4×a2)×(b×b2) 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×a4+2×b1+2 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×a6×b3 

=− 3/5 a6b3 

Thus, the answer is  − 3/5 a6b3

Question 13: Find each of the following product:

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Answer 13: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n.
We have:

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(a×a×a2)×(b2×b)×(c2×c) 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(a×a×a2)×(b2×b)×(c2×c) 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(a1+1+2)×(b2+1)×(c2+1) 

=a4b3c3 

Thus, the answer is a4b3c3-a4b3c3. 

Question 14: Find each of the following product:

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Answer 14: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e.,am×an=am+nam×an=am+n.
We have:

(4/3 u2vw)×(5uvw2)×(1/3 v2wu)  

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(u2×u×u)×(v×v×v2)×(w×w2×w) 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(u2+1+1)×(v1+1+2)×(w1+2+1) 

= 20/9 u4v4w4 

Thus, the answer is  20/9 u4v4w4 

Question 15: Find each of the following product:
(0.5x)×(1/3 xy2z4)×(24x2yz)0.5x×13xy2z4×24x2yz

Answer 15: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n.
We have: 

(0.5x)×(1/3 xy2z4)×(24x2yz) 

=(0.5×1/3×24)×(x×x×x2)×(y2×y)×(z4×z) 

=(0.5×1/3×24)×(x1+1+2)×(y2+1)×(z4+1) 

=4x4y3z5 

Thus, the answer is 4x4y3z54x4y3z5. 

Question 16: Find each of the following product:

(4/3 pq2)×(1/4 p2r)×(16p2q2r2)43pq2×-14p2r×16p2q2r2 

Answer 16: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n.
We have: 

(4/3 pq2)×(1/4 p2r)×(16p2q2r2)

={4/3×(−1/4)×16}×(p×p2×p2)×(q2×q2)×(r×r2) 

={4/3×(− 1/4)×16}×(p1+2+2)×(q2+2)×(r1+2) 

= 16/3p5q4r3 

Thus, the answer is 1/3 p5q4r3-13p5q4r3. 

Question 17: Find each of the following product:
(2.3xy) × (0.1x) × (0.16)

Answer 17: To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n.
We have:
(2.3xy)×(0.1x)×(0.16)=(2.3×0.1×0.16)×(x×x)×y=(2.3×0.1×0.16)×(x1+1)×y=0.0368x2y
Thus, the answer is 0.0368x2y0.0368x2y.

Question 18: Express each of the following product as a monomials and verify the result in each case for x = 1:
(3x) × (4x) × (−5x)

Answer 18: We have to find the product of the expression in order to express it as a monomial.
To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n.
We have:
(3x)×(4x)×(5x)={3×4×(5)}×(x×x×x)={3×4×(5)}×(x1+1+1)=60x33x×4x×-5x=3×4×-5×x×x×x=3×4×-5×x1+1+1=-60x3
Substituting x = 1 in LHS, we get:
LHS =(3x)×(4x)×(5x)
=(3×1)×(4×1)×(−5×1)

=−60
Putting x = 1 in RHS, we get:
RHS =60x3=60(1)3=60×1=60 LHS = RHS for = 1; therefore, the result is correct
Thus, the answer is 60x3-60x3. 

Question 19: Express each of the following product as a monomials and verify the result in each case for x = 1:
(4x2) × (−3x) × (4/5 x3)

Answer 19: We have to find the product of the expression in order to express it as a monomial.
To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e., am×an=am+nam×an=am+n. 

We  have: 

(4x2)×(3x)×(4/5 x3) 

={4×(3)×4/5}×(x2×x×x3) 

={4×(3)×4/5}×(x2+1+3)

=− 48/5x6  

(4x2)×(3x)×(4/5 x3)=− 48/5x6 

Substituting x = 1 in LHS, we get: 

LHS=(4x2)×(3x)×(4/5 x3) 

=(4×12)×(3×1)×(4/5 ×13) 

=4×(3)×4/5

=48/5

Putting x = 1 in RHS, we get: 

RHS= 48/5 x6 
=48/5×16 

=48/5

 LHS = RHS for = 1; therefore, the result is correct
Thus, the answer is − 48/5 x6-485x6. 

Question 20: Express each of the following product as a monomials and verify the result in each case for x = 1:
(5x4) × (x2)3 × (2x)2

Answer 20: We have to find the product of the expression in order to express it as a monomial.

To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e., am×an=am+n and (am)n=amn am×an=am+n and amn=amn .
We have:
(5x4)×(x2)3×(2x)2 =(5x4)×(x6)×(22×x2)=(5×22)×(x4×x6×x2)=(5×22)×(x4+6+2)=20x12
∴ (5x4)×(x2)3×(2x)2 =20x12 

Substituting x = 1 in LHS, we get:
LHS=(5x4)×(x2)3×(2x)2 =(5×14)×(12)3×(2×1)2 =(5×1)×(16)×(2)2 =5×1×4=20

Put x =1 in RHS, we getRHS =20x12=20×(1)12=20×1=20 LHS = RHS for = 1; therefore, the result is correct.

Thus, the answer is 20x1220x12. 

Question 21: Express each of the following product as a monomials and verify the result in each case for x = 1:
(x2)3 × (2x) × (−4x) × (5)

Answer 21: We have to find the product of the expression in order to express it as a monomial.
To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e.,am×an=am+n and (am)n=amn am×an=am+n and amn=amn .
We have: 

(x2)3×(2x)×(4x)×5=(x6)×(2x)×(4x)×5={2×(4)×5}×(x6×x×x)={2×(4)×5}×(x6+1+1)=40x8

 (x2)3×(2x)×(4x)×5=40x8x23×2x×-4x×5=-40x8    

Substituting x = 1 in LHS, we get: 

LHS =(x2)3×(2x)×(4x)×5=(12)3×(2×1)×(4×1)×5=16×2×(4)×5=1×2×(4)×5=40 Putting x = 1 in RHS, we get: 

RHS=40x8=40(1)8=40×1=40  LHS = RHS for = 1; therefore, the result is correct 

Thus, the answer is −40x8 .

Question 22: Write down the product of −8x2y6 and −20xyVerify the product for x = 2.5, y = 1. 

Answer 22: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e., am×an=am+nam×an=am+n. 

We have: 

(8x2y6)×(20xy)={(8)×(20)}×(x2×x)×(y6×y)={(8)×(20)}×(x2+1)×(y6+1)=160x3y7  (8x2y6)×(20xy)=160x3y7-8x2y6×-20xy=-160x3y7

Substituting x = 2.5 and y = 1 in LHS, we get: 

LHS=(8x2y6)×(20xy)={8(2.5)2(1)6}×{20(2.5)(1)}={8(6.25)(1)}×{20(2.5)(1)}=(50)×(50)=2500 Substituting x = 2.5 and y = 1 in RHS, we get: 

RHS=160x3y7=160(2.5)3(1)7=160(15.625)×1=2500 Because LHS is equal to RHS, the result is correct. 

Thus, the answer is 160x3y7-160x3y7. 

Question 23:Evaluate (3.2x6y3) × (2.1x2y2) when x = 1 and y = 0.5
Ans
First multiply the expressions and then substitute the values for the variables.
To multiply algebric experssions use the commutative and the associative laws along with the law of indices, am×an=am+nam×an=am+n.
We have,
(3.2x6y3)×(2.1x2y2)=(3.2×2.1)×(x6×x2)×(y3×y2)=6.72x8y53.2x6y3×2.1x2y2=3.2×2.1×x6×x2×y3×y2=6.72x8y5Hence, (3.2x6y3)×(2.1x2y2)=6.72x8y53.2x6y3×2.1x2y2=6.72x8y5
Now, substitute 1 for x and 0.5  for y in the result.
6.72x8y5

=6.72(1)8(0.5)5

=6.72×1×0.03125

=0.216.72x8y5=6.72180.55=6.72×1×0.03125=0.2Hence, the answer is 0.210.21.

Answer 23: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e., am×an=am+nam×an=am+n.
We have:
(3.2x6y3)×(2.1x2y2)=(3.2×2.1)×(x6×x2)×(y3×y2)=(3.2×2.1)×(x6+2)×(y3+2)=6.72x8y53.2x6y3×2.1x2y2=3.2×2.1×x6×x2×y3×y2=3.2×2.1×x6+2×y3+2=6.72x8y5
 (3.2x6y3)×(2.1x2y2)=6.72x8y53.2x6y3×2.1x2y2=6.72x8y5
Substituting x = 1 and y = 0.5 in the result, we get:
6.72x8y5

=6.72(1)8(0.5)5

=6.72×1×0.03125

=0.2172x8y5=6.72180.55=6.72×1×0.03125=0.21
Thus, the answer is 0.210.21. 

Question 24: Find the value of (5x6) × (−1.5x2y3) × (−12xy2) when x = 1, y = 0.5.

Answer 24: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e., am×an=am+nam×an=am+n.
We have:
(5x6)×(−1.5x2y3)×(−12xy2)

={5×(−1.5)×(−12)}×(x6×x2×x)×(y3×y2)

=5×(−1.5)×(−12)×(x6+2+1)×(y3+2)

=90x9y5
Substituting x = 1 and y = 0.5 in the result, we get:
90x9y5=90(1)9(0.5)5=90×1×0.03125=2.812590x9y5=90190.55=90×1×0.03125=2.8125
Thus, the answer is 2.8125. 

Question 25: Evaluate (2.3a5b2) × (1.2a2b2) when a = 1 and b = 0.5.

Answer 25: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e., am×an=am+nam×an=am+n.
We have:
(2.3a5b2)×(1.2a2b2)

=(2.3×1.2)×(a5×a2)×(b2×b2)

=(2.3×1.2)×(a5+2)×(b2+2)

=2.76a7b4
∴∴ (2.3a5b2)×(1.2a2b2)=2.76a7b4
Substituting a =1 and b = 0.5 in the result, we get:
2.76a7b4=2.76(1)7(0.5)4=2.76×1×0.0625=0.17252.76a7b4=2.76170.54=2.76×1×0.0625=0.1725
Thus, the answer is 0.17250.1725. 

Question 26: Evaluate (−8x2y6) × (−20xy) for x = 2.5 and y = 1.

Answer 26: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e.,am×an=am+nam×an=am+n.
We have:
(8x2y6)×(20xy)={(8)×(20)}×(x2×x)×(y6×y)={(8)×(20)}×(x2+1)×(y6+1)=160x3y7-8x2y6×-20xy=-8×-20×x2×x×y6×y=-8×-20×x2+1×y6+1=160x3y7
 (8x2y6)×(20xy)=160x3y7-8x2y6×-20xy=160x3y7
Substituting x = 2.5 and y = 1 in the result, we get:
160x3y7=160(2.5)3(1)7=160×15.625=2500160x3y7=1602.5317=160×15.625=2500
Thus, the answer is 25002500. 

Question 27: Express each of the following product as a monomials and verify the result for x = 1, y = 2:
(−xy3) × (yx3) × (xy)

Answer 27: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e.,am×an=am+nam×an=am+n.
We have:
(xy3)×(yx3)×(xy)=(1)×(x×x3×x)×(y3×y×y)=(1)×(x1+3+1)×(y3+1+1)=x5y5-xy3×yx3×xy=-1×x×x3×x×y3×y×y=-1×x1+3+1×y3+1+1=-x5y5
To verify the result, we substitute x = 1 and y = 2 in LHS; we get:
LHS =(xy3)×(yx3)×(xy)={(1)×1×23}×(2×13)×(1×2)={(1)×1×8}×(2×1)×2=(8)×2×2=32LHS =-xy3×yx3×xy=-1×1×23×2×13×1×2=-1×1×8×2×1×2=-8×2×2=-32
Substituting x = 1 and y = 2 in RHS, we get:
RHS=x5y5=(1)(1)5(2)5=(1)×1×32=32RHS=-x5y5=-11525=-1×1×32=-32
Because LHS is equal to RHS, the result is correct.
Thus, the answer is x5y5-x5y5. 

Question 28: Express each of the following product as a monomials and verify the result for x = 1, y = 2:

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Answer 28: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e., am×an=am+nam×an=am+n. 

We have: 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(x2×x4×x)×(y4×y2×y) 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(x2+4+1)×(y4+2+1) 

= 5/32 x7y7 

To verify the result, we substitute x = 1 and y = 2 in LHS; we get: 

LHS= RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(xy)×5 

={1/8×(1)2×(2)4}×{1/4×(1)4×(2)2}×(1×2)×5 

=(1/8×1×16)×(1/4 ×1×4)×(1×2)×5 

=2×1×2×5=20 Substituting x = 1 and y = 2 in RHS, we get: 

RHS=5/32 x7y7 

=5/32 (1)7(2)7 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics 

=20 

Because LHS is equal to RHS, the result is correct.
Thus, the answer is 5/32 x7y7532x7y7. 

Question 29: Express each of the following product as a monomials and verify the result for x = 1, y = 2:

(2/5 a2b)×(15b2ac)×(1/2 c2)25a2b×-15b2ac×-12c2 

Answer 29: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e., am×an=am+nam×an=am+n. 

We have: 

(2/5 a2b)×(15b2ac)×(1/2 c2) 

={2/5 ×(15)×(−1/2)}×(a2×a)×(b×b2)×(c×c2) 

={2/5 ×(15)×(−1/2)}×(a2+1)×(b1+2)×(c1+2)

=3a3b3c3 

 The expression doesn't consist of the variables x and y. 

 The result cannot be verified for = 1 and = 2 

Thus, the answer is 3a3b3c33a3b3c3. 

Question 30: Express each of the following product as a monomials and verify the result for x = 1, y = 2:

 (4/7 a2b)×(2/3 b2c)×(7/6 c2a)-47a2b×-23b2c×-76c2a 

Answer 30: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e., am×an=am+nam×an=am+n. 

We have: 

(4/7 a2b)×(2/3 b2c)×(7/6 c2a) 

={(−4/7)×(−2/3)×(−7/6)}×(a2×a)×(b×b2)×(c×c2) 

={(−4/7)×(−2/3)×(−7/6)}×(a2+1)×(b1+2)×(c1+2) 

=4/9a3b3c3 

 The expression doesn't consist of the variables x and y.
 The result cannot be verified for = 1 and = 2.  

 Thus, the answer is 4/9a3b3c3-49a3b3c3. 

Question 31: Express each of the following product as a monomials and verify the result for x = 1, y = 2:

(4/9 abc3)×(27/5a3b2)×(8b3c)49abc3×-275a3b2×-8b3c 

Answer 31: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e., am×an=am+nam×an=am+n.

We have: 

(4/9 abc3)×(27/5 a3b2)×(8b3c) 

={(4/9)×(−27/5)×(8)}×(a×a3)×(b×b2×b3)×(c3×c) 

={(4/9)×(−27/5)×(8)}×(a1+3)×(b1+2+3)×(c3+1)

=96/5 a4b6c4  

Thus, the answer is 96/5  a4b6c4965a4b6c4. 

 The expression doesn't consist of the variables x and y.

 The result cannot be verified for = 1 and = 2 

Question 32: Evaluate each of the following when x = 2, y = −1. 

(2xy)×RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics×(x2)×(y2)(2xy)×x2y4×x2×y2 

Answer 32: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e., am×an=am+nam×an=am+n.

We have: 

(2xy)×RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics×(x2)×(y2) 

=(2×1/4)×(x×x2×x2)×(y×y×y2)

 
(
2×1/4)
×(x1+2+2)×(y1+1+2) 

=1/2 x5y4 

 (2xy)×RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics×(x2)×(y2)=12x5y42xy×x2y4×x2×y2=12x5y4

Substituting x = 2 and y = -1 in the result, we get: 

1/2 x5y4 

=1/2 (2)5(1)4 

=1/2×32×1 

16

Thus, the answer is 1616. 

Question 33: Evaluate each of the following when x = 2, y = −1.

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Answer 33: To multiply algebraic expressions, we use commutative and associative laws along with the laws of indices, i.e., am×an=am+nam×an=am+n. 

We have: 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(x2×x×x2)×(y×y2×y2) 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics ×(x2+1+2)×(y1+2+2) 

= 7/4 x5y5 

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

Substituting x = 2 and y = -1 in the result, we get: 

7/4 x5y5 

=7/4 (2)5(1)5 

=(−7/4)×32×(1) 

= 56

Thus, the answer is 56. 2a3=-5×-10×-2×a×a2×a3=-5×-10×-2×a1+2+3=-100a6

The document RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics is a part of the Class 8 Course RD Sharma Solutions for Class 8 Mathematics.
All you need of Class 8 at this link: Class 8
88 docs

Top Courses for Class 8

Explore Courses for Class 8 exam

Top Courses for Class 8

Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev
Related Searches

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

,

Viva Questions

,

Summary

,

video lectures

,

MCQs

,

Semester Notes

,

ppt

,

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

,

mock tests for examination

,

shortcuts and tricks

,

Previous Year Questions with Solutions

,

study material

,

practice quizzes

,

pdf

,

Objective type Questions

,

past year papers

,

Important questions

,

Exam

,

Sample Paper

,

RD Sharma Solutions for Class 8 Math Chapter 6 - Algebraic Expressions and Identities (Part-2) | RD Sharma Solutions for Class 8 Mathematics

,

Extra Questions

,

Free

;