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RS Aggarwal Solutions: Algebraic Expressions | Mathematics (Maths) Class 7 PDF Download

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 Page 1


Question:1
Add the following expressions:
i
5x, 7x, -6x
ii
3
5
x,
2
3
x,
-4
5
x
iii
5a
2
b, -8a
2
b, 7a
2
b
iv
3
4
x
2
, 5x
2
, -3x
2
, -
1
4
x
2
v
x - 3y + 4z, y - 2x - 8z, 5x - 2y - 3z
vi
2x
2
 - 3y
2
, 5x
2
 + 6y
2
, - 3x
2
 - 4y
2
vii
5x - 2x
2
 - 8, 8x
2 
- 7x - 9, 3 + 7x
2
 - 2x
viii
2
3
a -
4
5
b +
3
5
c, -
3
4
a -
5
2
b +
2
3
c,
5
2
a +
7
4
b -
5
6
c
ix
8
5
x +
11
7
y +
9
4
xy, -
3
2
x -
5
3
y -
9
5
xy
x
3
2
x
3
-
1
4
x
2
+
5
3
, -
5
4
x
3
+
3
5
x
2
-x +
1
5
, -x
2
+
3
8
x -
8
15
Solution:
i
  5x + 7x + -6x
= 5x + 7x -6x
= 6x
ii
 
3
5
x +
2
3
x +
-4
5
x =
9x +10x -12x
15
=
7x
15
iii
 
5a
2
b +( -8a
2
b)  + 7a
2
b
= 5a
2
b - 8a
2
b + 7a
2
b
4a
2
b
iv
 
3
4
x
2
 + 5x
2
+ -3x
2 
 + -
1
4
x
2
=
3
4
x
2
 - 
1
4
x
2
 + 5x
2
-3x
2
=
1
2
x
2
 + 2x
2
 = 
5
2
x
2
v Collecting like terms and adding them:
x - 3y + 4z + y - 2x - 8z + 5x - 2y - 3z
= x- 2x + 5x - 3y + y - 2y + 4z - 8z - 3z        
= 4x -4y -7z
vi
 Collecting like terms and adding them:
2x
2
 - 3y
2
 + 5x
2
 + 6y
2
 + (- 3x
2
 - 4y
2
)
 = 2x
2
 + 5x
2
 - 3x
2
 - 3y
2
 +6y
2
 -4y
2
= 4x
2
 -y
2
                   
vii
Collecting like terms and adding them:
5x - 2x
2
 - 8 +  8x
2 
- 7x - 9 +  3 + 7x
2
 - 2x
= -2x
2 
+8x
2
 + 7x
2
 + 5x - 7x - 2x -8 -9 + 3 = 13x
2
 -4x -14
      
viii
 Collecting like terms and adding them:
2
3
a -
4
5
b +
3
5
c + -
3
4
a -
5
2
b +
2
3
c + 
5
2
a +
7
4
b - 
5
6
c   b -
5
2
b +
7
4
b +
3
5
c +
2
3
c - 
5
6
c =
(8 -9 +30)a
12
 + 
(-16 - 50 +35)b
20
 + 
(18 +20 -25)c
30
=
29
12
a - 
31
20
b + 
13
30
c
ix
Collecting like terms and adding them:
8
5
( ) ( )
( )
Page 2


Question:1
Add the following expressions:
i
5x, 7x, -6x
ii
3
5
x,
2
3
x,
-4
5
x
iii
5a
2
b, -8a
2
b, 7a
2
b
iv
3
4
x
2
, 5x
2
, -3x
2
, -
1
4
x
2
v
x - 3y + 4z, y - 2x - 8z, 5x - 2y - 3z
vi
2x
2
 - 3y
2
, 5x
2
 + 6y
2
, - 3x
2
 - 4y
2
vii
5x - 2x
2
 - 8, 8x
2 
- 7x - 9, 3 + 7x
2
 - 2x
viii
2
3
a -
4
5
b +
3
5
c, -
3
4
a -
5
2
b +
2
3
c,
5
2
a +
7
4
b -
5
6
c
ix
8
5
x +
11
7
y +
9
4
xy, -
3
2
x -
5
3
y -
9
5
xy
x
3
2
x
3
-
1
4
x
2
+
5
3
, -
5
4
x
3
+
3
5
x
2
-x +
1
5
, -x
2
+
3
8
x -
8
15
Solution:
i
  5x + 7x + -6x
= 5x + 7x -6x
= 6x
ii
 
3
5
x +
2
3
x +
-4
5
x =
9x +10x -12x
15
=
7x
15
iii
 
5a
2
b +( -8a
2
b)  + 7a
2
b
= 5a
2
b - 8a
2
b + 7a
2
b
4a
2
b
iv
 
3
4
x
2
 + 5x
2
+ -3x
2 
 + -
1
4
x
2
=
3
4
x
2
 - 
1
4
x
2
 + 5x
2
-3x
2
=
1
2
x
2
 + 2x
2
 = 
5
2
x
2
v Collecting like terms and adding them:
x - 3y + 4z + y - 2x - 8z + 5x - 2y - 3z
= x- 2x + 5x - 3y + y - 2y + 4z - 8z - 3z        
= 4x -4y -7z
vi
 Collecting like terms and adding them:
2x
2
 - 3y
2
 + 5x
2
 + 6y
2
 + (- 3x
2
 - 4y
2
)
 = 2x
2
 + 5x
2
 - 3x
2
 - 3y
2
 +6y
2
 -4y
2
= 4x
2
 -y
2
                   
vii
Collecting like terms and adding them:
5x - 2x
2
 - 8 +  8x
2 
- 7x - 9 +  3 + 7x
2
 - 2x
= -2x
2 
+8x
2
 + 7x
2
 + 5x - 7x - 2x -8 -9 + 3 = 13x
2
 -4x -14
      
viii
 Collecting like terms and adding them:
2
3
a -
4
5
b +
3
5
c + -
3
4
a -
5
2
b +
2
3
c + 
5
2
a +
7
4
b - 
5
6
c   b -
5
2
b +
7
4
b +
3
5
c +
2
3
c - 
5
6
c =
(8 -9 +30)a
12
 + 
(-16 - 50 +35)b
20
 + 
(18 +20 -25)c
30
=
29
12
a - 
31
20
b + 
13
30
c
ix
Collecting like terms and adding them:
8
5
( ) ( )
( )
x + 
11
7
y +
9
4
xy + 
(
- 
3
2
x - 
5
3
y -
9
5
xy
)
=
8
5
x - 
3
2
x + 
11
7
y - 
5
3
y +
9
4
xy -
9
5
xy = 
1
10
x - 
2
21
y + 
9
20
xy
(x) Collecting like terms and adding them:
3
2
x
3
-
1
4
x
2
 +
5
3
+
(
- 
5
4
x
3
+
3
5
x
2
- x +
1
5
)
+
(
- x
2  
+
3
8
x -
8
15
)
= 
3
2
x
3
 - 
5
4
x
3
 -
1
4
x
2
 +
3
5
x
2
- x
2  
- x +
3
8
x +
5
3
+
1
Page 3


Question:1
Add the following expressions:
i
5x, 7x, -6x
ii
3
5
x,
2
3
x,
-4
5
x
iii
5a
2
b, -8a
2
b, 7a
2
b
iv
3
4
x
2
, 5x
2
, -3x
2
, -
1
4
x
2
v
x - 3y + 4z, y - 2x - 8z, 5x - 2y - 3z
vi
2x
2
 - 3y
2
, 5x
2
 + 6y
2
, - 3x
2
 - 4y
2
vii
5x - 2x
2
 - 8, 8x
2 
- 7x - 9, 3 + 7x
2
 - 2x
viii
2
3
a -
4
5
b +
3
5
c, -
3
4
a -
5
2
b +
2
3
c,
5
2
a +
7
4
b -
5
6
c
ix
8
5
x +
11
7
y +
9
4
xy, -
3
2
x -
5
3
y -
9
5
xy
x
3
2
x
3
-
1
4
x
2
+
5
3
, -
5
4
x
3
+
3
5
x
2
-x +
1
5
, -x
2
+
3
8
x -
8
15
Solution:
i
  5x + 7x + -6x
= 5x + 7x -6x
= 6x
ii
 
3
5
x +
2
3
x +
-4
5
x =
9x +10x -12x
15
=
7x
15
iii
 
5a
2
b +( -8a
2
b)  + 7a
2
b
= 5a
2
b - 8a
2
b + 7a
2
b
4a
2
b
iv
 
3
4
x
2
 + 5x
2
+ -3x
2 
 + -
1
4
x
2
=
3
4
x
2
 - 
1
4
x
2
 + 5x
2
-3x
2
=
1
2
x
2
 + 2x
2
 = 
5
2
x
2
v Collecting like terms and adding them:
x - 3y + 4z + y - 2x - 8z + 5x - 2y - 3z
= x- 2x + 5x - 3y + y - 2y + 4z - 8z - 3z        
= 4x -4y -7z
vi
 Collecting like terms and adding them:
2x
2
 - 3y
2
 + 5x
2
 + 6y
2
 + (- 3x
2
 - 4y
2
)
 = 2x
2
 + 5x
2
 - 3x
2
 - 3y
2
 +6y
2
 -4y
2
= 4x
2
 -y
2
                   
vii
Collecting like terms and adding them:
5x - 2x
2
 - 8 +  8x
2 
- 7x - 9 +  3 + 7x
2
 - 2x
= -2x
2 
+8x
2
 + 7x
2
 + 5x - 7x - 2x -8 -9 + 3 = 13x
2
 -4x -14
      
viii
 Collecting like terms and adding them:
2
3
a -
4
5
b +
3
5
c + -
3
4
a -
5
2
b +
2
3
c + 
5
2
a +
7
4
b - 
5
6
c   b -
5
2
b +
7
4
b +
3
5
c +
2
3
c - 
5
6
c =
(8 -9 +30)a
12
 + 
(-16 - 50 +35)b
20
 + 
(18 +20 -25)c
30
=
29
12
a - 
31
20
b + 
13
30
c
ix
Collecting like terms and adding them:
8
5
( ) ( )
( )
x + 
11
7
y +
9
4
xy + 
(
- 
3
2
x - 
5
3
y -
9
5
xy
)
=
8
5
x - 
3
2
x + 
11
7
y - 
5
3
y +
9
4
xy -
9
5
xy = 
1
10
x - 
2
21
y + 
9
20
xy
(x) Collecting like terms and adding them:
3
2
x
3
-
1
4
x
2
 +
5
3
+
(
- 
5
4
x
3
+
3
5
x
2
- x +
1
5
)
+
(
- x
2  
+
3
8
x -
8
15
)
= 
3
2
x
3
 - 
5
4
x
3
 -
1
4
x
2
 +
3
5
x
2
- x
2  
- x +
3
8
x +
5
3
+
1
5
-
8
15
=
1
4
x
3
 - 
13
20
x
2
 -
5
8
x +
4
3
Question:2
Subtract:
i
-8xy from 7xy
ii
x
2
 from - 3x
2
iii
(x - y) from (4y - 5x)
iv
(a
2 
+ b
2
 - 2ab) from (a
2
 + b
2
 + 2ab)
v
(x
2
 - y
2
) from (2x
2
 - 3y
2
 + 6xy)
vi
(x - y + 3z) from (2z - x - 3y)
Solution:
i
7xy- -8xy
= 7xy+ 8xy
= 15xy
ii
  - 3x
2
 - x
2
= -4x
2
iii 
4y - 5x -
x - y
= 4y - 5x - x + y
= 5y - 6x
iv 
(a
2
 + b
2
 + 2ab) - (a
2 
+ b
2
 - 2ab)
=
a
2
 -a
2
 +b
2
 -b
2
 + 2ab + 2ab    Collectingliketermsandaddingthem
= 4ab
v (2x
2
 - 3y
2
 + 6xy) -  (x
2
 - y
2
)
2x
2
 - x
2
 - 3y
2
 + y
2
 +6xy = x
2
 -2y
2
 +6xy
     Collectingliketermsandaddingthem
vi
  2z -x -3y
- x -y +3z
= 2z -3z -x -x -3y +y       Collectingliketermsandaddingthem
= -z -2x - 2y
 
Question:3
Subtract (2a - 3b + 4c) from the sum of (a + 3b - 4c), (4a - b + 9c) and (-2b + 3c - a).
Solution:
(a + 3b - 4c) + (4a - b + 9c) + (-2b + 3c - a)
= a + 4a - a + 3b -b -2b -4c +9c + 3c
= 4a + 8c
Now,  4a +8c
- (2a - 3b + 4c)
= 4a - 2a + 3b + 8c - 4c
= 2a + 3b + 4c
Question:4
Subtract the sum of (8m - 7n + 6p
2
) and (-3m - 4n - p
2
) from the sum of (2m + 4n - 3p
2
) and (- m - n - p
2
).
Solution:
(8m - 7n + 6p
2
) + (-3m - 4n - p
2
)
 = 8m - 3m - 7n -4n + 6p
2
 - p 
2
= 5m -11n +5p
2
 
(2m + 4n - 3p
2
) + (- m - n - p
2
).
x + y + xy , - x - y -
Page 4


Question:1
Add the following expressions:
i
5x, 7x, -6x
ii
3
5
x,
2
3
x,
-4
5
x
iii
5a
2
b, -8a
2
b, 7a
2
b
iv
3
4
x
2
, 5x
2
, -3x
2
, -
1
4
x
2
v
x - 3y + 4z, y - 2x - 8z, 5x - 2y - 3z
vi
2x
2
 - 3y
2
, 5x
2
 + 6y
2
, - 3x
2
 - 4y
2
vii
5x - 2x
2
 - 8, 8x
2 
- 7x - 9, 3 + 7x
2
 - 2x
viii
2
3
a -
4
5
b +
3
5
c, -
3
4
a -
5
2
b +
2
3
c,
5
2
a +
7
4
b -
5
6
c
ix
8
5
x +
11
7
y +
9
4
xy, -
3
2
x -
5
3
y -
9
5
xy
x
3
2
x
3
-
1
4
x
2
+
5
3
, -
5
4
x
3
+
3
5
x
2
-x +
1
5
, -x
2
+
3
8
x -
8
15
Solution:
i
  5x + 7x + -6x
= 5x + 7x -6x
= 6x
ii
 
3
5
x +
2
3
x +
-4
5
x =
9x +10x -12x
15
=
7x
15
iii
 
5a
2
b +( -8a
2
b)  + 7a
2
b
= 5a
2
b - 8a
2
b + 7a
2
b
4a
2
b
iv
 
3
4
x
2
 + 5x
2
+ -3x
2 
 + -
1
4
x
2
=
3
4
x
2
 - 
1
4
x
2
 + 5x
2
-3x
2
=
1
2
x
2
 + 2x
2
 = 
5
2
x
2
v Collecting like terms and adding them:
x - 3y + 4z + y - 2x - 8z + 5x - 2y - 3z
= x- 2x + 5x - 3y + y - 2y + 4z - 8z - 3z        
= 4x -4y -7z
vi
 Collecting like terms and adding them:
2x
2
 - 3y
2
 + 5x
2
 + 6y
2
 + (- 3x
2
 - 4y
2
)
 = 2x
2
 + 5x
2
 - 3x
2
 - 3y
2
 +6y
2
 -4y
2
= 4x
2
 -y
2
                   
vii
Collecting like terms and adding them:
5x - 2x
2
 - 8 +  8x
2 
- 7x - 9 +  3 + 7x
2
 - 2x
= -2x
2 
+8x
2
 + 7x
2
 + 5x - 7x - 2x -8 -9 + 3 = 13x
2
 -4x -14
      
viii
 Collecting like terms and adding them:
2
3
a -
4
5
b +
3
5
c + -
3
4
a -
5
2
b +
2
3
c + 
5
2
a +
7
4
b - 
5
6
c   b -
5
2
b +
7
4
b +
3
5
c +
2
3
c - 
5
6
c =
(8 -9 +30)a
12
 + 
(-16 - 50 +35)b
20
 + 
(18 +20 -25)c
30
=
29
12
a - 
31
20
b + 
13
30
c
ix
Collecting like terms and adding them:
8
5
( ) ( )
( )
x + 
11
7
y +
9
4
xy + 
(
- 
3
2
x - 
5
3
y -
9
5
xy
)
=
8
5
x - 
3
2
x + 
11
7
y - 
5
3
y +
9
4
xy -
9
5
xy = 
1
10
x - 
2
21
y + 
9
20
xy
(x) Collecting like terms and adding them:
3
2
x
3
-
1
4
x
2
 +
5
3
+
(
- 
5
4
x
3
+
3
5
x
2
- x +
1
5
)
+
(
- x
2  
+
3
8
x -
8
15
)
= 
3
2
x
3
 - 
5
4
x
3
 -
1
4
x
2
 +
3
5
x
2
- x
2  
- x +
3
8
x +
5
3
+
1
5
-
8
15
=
1
4
x
3
 - 
13
20
x
2
 -
5
8
x +
4
3
Question:2
Subtract:
i
-8xy from 7xy
ii
x
2
 from - 3x
2
iii
(x - y) from (4y - 5x)
iv
(a
2 
+ b
2
 - 2ab) from (a
2
 + b
2
 + 2ab)
v
(x
2
 - y
2
) from (2x
2
 - 3y
2
 + 6xy)
vi
(x - y + 3z) from (2z - x - 3y)
Solution:
i
7xy- -8xy
= 7xy+ 8xy
= 15xy
ii
  - 3x
2
 - x
2
= -4x
2
iii 
4y - 5x -
x - y
= 4y - 5x - x + y
= 5y - 6x
iv 
(a
2
 + b
2
 + 2ab) - (a
2 
+ b
2
 - 2ab)
=
a
2
 -a
2
 +b
2
 -b
2
 + 2ab + 2ab    Collectingliketermsandaddingthem
= 4ab
v (2x
2
 - 3y
2
 + 6xy) -  (x
2
 - y
2
)
2x
2
 - x
2
 - 3y
2
 + y
2
 +6xy = x
2
 -2y
2
 +6xy
     Collectingliketermsandaddingthem
vi
  2z -x -3y
- x -y +3z
= 2z -3z -x -x -3y +y       Collectingliketermsandaddingthem
= -z -2x - 2y
 
Question:3
Subtract (2a - 3b + 4c) from the sum of (a + 3b - 4c), (4a - b + 9c) and (-2b + 3c - a).
Solution:
(a + 3b - 4c) + (4a - b + 9c) + (-2b + 3c - a)
= a + 4a - a + 3b -b -2b -4c +9c + 3c
= 4a + 8c
Now,  4a +8c
- (2a - 3b + 4c)
= 4a - 2a + 3b + 8c - 4c
= 2a + 3b + 4c
Question:4
Subtract the sum of (8m - 7n + 6p
2
) and (-3m - 4n - p
2
) from the sum of (2m + 4n - 3p
2
) and (- m - n - p
2
).
Solution:
(8m - 7n + 6p
2
) + (-3m - 4n - p
2
)
 = 8m - 3m - 7n -4n + 6p
2
 - p 
2
= 5m -11n +5p
2
 
(2m + 4n - 3p
2
) + (- m - n - p
2
).
x + y + xy , - x - y -
 = 2m -m + 4n -n -3p
2
 -p
2
= m + 3n -4p
2
Now, m + 3n - 4p
2
 - 5m -11n +5p
2
= -4m +14n -9p
2
Question:5
Subtract the sum of (8a - 6a
2
 + 9) and (-10a - 8 + 8a
2
) from -3.
Solution:
(8a - 6a
2
 + 9)+  (-10a - 8 + 8a
2
)
Collecting like terms and adding them:
 8a -10a -6a
2
 + 8a
2
 +9 -8 = -2a + 2a
2
 + 1Now, -3 - -2a + 2a
2
 + 1 = 2a - 2a
2
 -4
Question:6
Simplify:
i
(5x -9y) - (-7x + y)
ii
x
2
-x -
1
2
x -3 +3x
2
iii
[7 - 2x + 5y - (x - y)] - (5x + 3y - 7)
iv
1
3
y
2
-
4
7
y +5 -
2
7
y -
2
3
y
2
+2 -
1
7
y -3 +2y
2
Solution:
Collecting like terms and adding them:
i
  5x + 7x - 9y -y
= 12x -10y
ii
x
2
 -
3
2
x
2
 -x -
1
2
x +
3
2
= -
1
2
x
2
 - 
3
2
x + 
3
2
iii
  7 + 7 - 2x -x - 5x + 5y + y - 3y
= 14 - 8x -3y
iv
 
1
3
y
2
 +
2
3
y
2
 -2y
2
 - 
4
7
y - 
2
7
y -
1
7
y +5 -2 +3 = - y
2
 - y +6
Question:7
Find the products:
3a
2
 × 8a
4
Solution:
3a
2
 × 8a
4
= 3× 8 × a
2
× a
4
= 24 × a
(2+4)
= 24a
6
Question:8
Find the products:
-6x
3
 × 5x
2
Solution:
-6x
3
 × 5x
2
= - 6× 5 × x
3
× x
2
= - 30 × x
(3+2)
= - 30x
5
Question:9
Find the products:
(-4ab) × (-3a
2
bc)
Solution:
(-4ab) × (-3a
2
bc)
= -4 × -3 × a ×a
2
×b ×b ×c = 12 × a
3
b
2
c = 12a
3
b
2
c
Question:10
Find the products:
(2a
2
b
3
) × (-3a
3
b)
Solution:
(2a
2
b
3
) × (-3a
3
b)
= 2 × -3 × a
2
×a
3
×b
3
×b = -6 × a
(2+3)
×b
(3+1)
= -6a
5
b
4
( ) ( )
( )
( ) ( )
( ) ( ) ( )
( ) ( )
( ) ( ) ( ) ( )
( ) ( ) ( )
( ( ) ) ( ) ( ) ( )
Page 5


Question:1
Add the following expressions:
i
5x, 7x, -6x
ii
3
5
x,
2
3
x,
-4
5
x
iii
5a
2
b, -8a
2
b, 7a
2
b
iv
3
4
x
2
, 5x
2
, -3x
2
, -
1
4
x
2
v
x - 3y + 4z, y - 2x - 8z, 5x - 2y - 3z
vi
2x
2
 - 3y
2
, 5x
2
 + 6y
2
, - 3x
2
 - 4y
2
vii
5x - 2x
2
 - 8, 8x
2 
- 7x - 9, 3 + 7x
2
 - 2x
viii
2
3
a -
4
5
b +
3
5
c, -
3
4
a -
5
2
b +
2
3
c,
5
2
a +
7
4
b -
5
6
c
ix
8
5
x +
11
7
y +
9
4
xy, -
3
2
x -
5
3
y -
9
5
xy
x
3
2
x
3
-
1
4
x
2
+
5
3
, -
5
4
x
3
+
3
5
x
2
-x +
1
5
, -x
2
+
3
8
x -
8
15
Solution:
i
  5x + 7x + -6x
= 5x + 7x -6x
= 6x
ii
 
3
5
x +
2
3
x +
-4
5
x =
9x +10x -12x
15
=
7x
15
iii
 
5a
2
b +( -8a
2
b)  + 7a
2
b
= 5a
2
b - 8a
2
b + 7a
2
b
4a
2
b
iv
 
3
4
x
2
 + 5x
2
+ -3x
2 
 + -
1
4
x
2
=
3
4
x
2
 - 
1
4
x
2
 + 5x
2
-3x
2
=
1
2
x
2
 + 2x
2
 = 
5
2
x
2
v Collecting like terms and adding them:
x - 3y + 4z + y - 2x - 8z + 5x - 2y - 3z
= x- 2x + 5x - 3y + y - 2y + 4z - 8z - 3z        
= 4x -4y -7z
vi
 Collecting like terms and adding them:
2x
2
 - 3y
2
 + 5x
2
 + 6y
2
 + (- 3x
2
 - 4y
2
)
 = 2x
2
 + 5x
2
 - 3x
2
 - 3y
2
 +6y
2
 -4y
2
= 4x
2
 -y
2
                   
vii
Collecting like terms and adding them:
5x - 2x
2
 - 8 +  8x
2 
- 7x - 9 +  3 + 7x
2
 - 2x
= -2x
2 
+8x
2
 + 7x
2
 + 5x - 7x - 2x -8 -9 + 3 = 13x
2
 -4x -14
      
viii
 Collecting like terms and adding them:
2
3
a -
4
5
b +
3
5
c + -
3
4
a -
5
2
b +
2
3
c + 
5
2
a +
7
4
b - 
5
6
c   b -
5
2
b +
7
4
b +
3
5
c +
2
3
c - 
5
6
c =
(8 -9 +30)a
12
 + 
(-16 - 50 +35)b
20
 + 
(18 +20 -25)c
30
=
29
12
a - 
31
20
b + 
13
30
c
ix
Collecting like terms and adding them:
8
5
( ) ( )
( )
x + 
11
7
y +
9
4
xy + 
(
- 
3
2
x - 
5
3
y -
9
5
xy
)
=
8
5
x - 
3
2
x + 
11
7
y - 
5
3
y +
9
4
xy -
9
5
xy = 
1
10
x - 
2
21
y + 
9
20
xy
(x) Collecting like terms and adding them:
3
2
x
3
-
1
4
x
2
 +
5
3
+
(
- 
5
4
x
3
+
3
5
x
2
- x +
1
5
)
+
(
- x
2  
+
3
8
x -
8
15
)
= 
3
2
x
3
 - 
5
4
x
3
 -
1
4
x
2
 +
3
5
x
2
- x
2  
- x +
3
8
x +
5
3
+
1
5
-
8
15
=
1
4
x
3
 - 
13
20
x
2
 -
5
8
x +
4
3
Question:2
Subtract:
i
-8xy from 7xy
ii
x
2
 from - 3x
2
iii
(x - y) from (4y - 5x)
iv
(a
2 
+ b
2
 - 2ab) from (a
2
 + b
2
 + 2ab)
v
(x
2
 - y
2
) from (2x
2
 - 3y
2
 + 6xy)
vi
(x - y + 3z) from (2z - x - 3y)
Solution:
i
7xy- -8xy
= 7xy+ 8xy
= 15xy
ii
  - 3x
2
 - x
2
= -4x
2
iii 
4y - 5x -
x - y
= 4y - 5x - x + y
= 5y - 6x
iv 
(a
2
 + b
2
 + 2ab) - (a
2 
+ b
2
 - 2ab)
=
a
2
 -a
2
 +b
2
 -b
2
 + 2ab + 2ab    Collectingliketermsandaddingthem
= 4ab
v (2x
2
 - 3y
2
 + 6xy) -  (x
2
 - y
2
)
2x
2
 - x
2
 - 3y
2
 + y
2
 +6xy = x
2
 -2y
2
 +6xy
     Collectingliketermsandaddingthem
vi
  2z -x -3y
- x -y +3z
= 2z -3z -x -x -3y +y       Collectingliketermsandaddingthem
= -z -2x - 2y
 
Question:3
Subtract (2a - 3b + 4c) from the sum of (a + 3b - 4c), (4a - b + 9c) and (-2b + 3c - a).
Solution:
(a + 3b - 4c) + (4a - b + 9c) + (-2b + 3c - a)
= a + 4a - a + 3b -b -2b -4c +9c + 3c
= 4a + 8c
Now,  4a +8c
- (2a - 3b + 4c)
= 4a - 2a + 3b + 8c - 4c
= 2a + 3b + 4c
Question:4
Subtract the sum of (8m - 7n + 6p
2
) and (-3m - 4n - p
2
) from the sum of (2m + 4n - 3p
2
) and (- m - n - p
2
).
Solution:
(8m - 7n + 6p
2
) + (-3m - 4n - p
2
)
 = 8m - 3m - 7n -4n + 6p
2
 - p 
2
= 5m -11n +5p
2
 
(2m + 4n - 3p
2
) + (- m - n - p
2
).
x + y + xy , - x - y -
 = 2m -m + 4n -n -3p
2
 -p
2
= m + 3n -4p
2
Now, m + 3n - 4p
2
 - 5m -11n +5p
2
= -4m +14n -9p
2
Question:5
Subtract the sum of (8a - 6a
2
 + 9) and (-10a - 8 + 8a
2
) from -3.
Solution:
(8a - 6a
2
 + 9)+  (-10a - 8 + 8a
2
)
Collecting like terms and adding them:
 8a -10a -6a
2
 + 8a
2
 +9 -8 = -2a + 2a
2
 + 1Now, -3 - -2a + 2a
2
 + 1 = 2a - 2a
2
 -4
Question:6
Simplify:
i
(5x -9y) - (-7x + y)
ii
x
2
-x -
1
2
x -3 +3x
2
iii
[7 - 2x + 5y - (x - y)] - (5x + 3y - 7)
iv
1
3
y
2
-
4
7
y +5 -
2
7
y -
2
3
y
2
+2 -
1
7
y -3 +2y
2
Solution:
Collecting like terms and adding them:
i
  5x + 7x - 9y -y
= 12x -10y
ii
x
2
 -
3
2
x
2
 -x -
1
2
x +
3
2
= -
1
2
x
2
 - 
3
2
x + 
3
2
iii
  7 + 7 - 2x -x - 5x + 5y + y - 3y
= 14 - 8x -3y
iv
 
1
3
y
2
 +
2
3
y
2
 -2y
2
 - 
4
7
y - 
2
7
y -
1
7
y +5 -2 +3 = - y
2
 - y +6
Question:7
Find the products:
3a
2
 × 8a
4
Solution:
3a
2
 × 8a
4
= 3× 8 × a
2
× a
4
= 24 × a
(2+4)
= 24a
6
Question:8
Find the products:
-6x
3
 × 5x
2
Solution:
-6x
3
 × 5x
2
= - 6× 5 × x
3
× x
2
= - 30 × x
(3+2)
= - 30x
5
Question:9
Find the products:
(-4ab) × (-3a
2
bc)
Solution:
(-4ab) × (-3a
2
bc)
= -4 × -3 × a ×a
2
×b ×b ×c = 12 × a
3
b
2
c = 12a
3
b
2
c
Question:10
Find the products:
(2a
2
b
3
) × (-3a
3
b)
Solution:
(2a
2
b
3
) × (-3a
3
b)
= 2 × -3 × a
2
×a
3
×b
3
×b = -6 × a
(2+3)
×b
(3+1)
= -6a
5
b
4
( ) ( )
( )
( ) ( )
( ) ( ) ( )
( ) ( )
( ) ( ) ( ) ( )
( ) ( ) ( )
( ( ) ) ( ) ( ) ( )
Question:11
Find the products:
2
3
x
2
y ×
3
5
xy
2
Solution:
=
2
3
×
3
5
× x
2
×x ×y ×y
2)
=
2
5
×x
(2+1)
×y
(1+2)
=
2
5
x
3
y
3
Question:12
Find the products:
-3
4
ab
3
×
-2
3
a
2
b
4
Solution:
=
-3
4
×
-2
3
× a ×a
2
×b
3
×b
4
=
1
2
×a
(1+2)
×b
(3+4)
=
1
2
a
3
b
7
Question:13
Find the products:
-1
27
a
2
b
2
×
-9
2
a
3
bc
2
Solution:
=
-1
27
×
-9
2
× a
2
×a
3
×b
2
×b ×c
2
=
1
6
×a
(2+3)
×b
(2+1)
×c
2
=
1
6
a
5
b
3
c
2
Question:14
Find the products:
-13
5
ab
2
c ×
7
3
a
2
bc
2
Solution:
=
-13
5
×
7
3
× a ×a
2
×b
2
×b ×c ×c
2
=
-91
15
a
(1+2)
×b
(2+1)
×c
(1+2)
=
-91
15
a
3
b
3
c
3
Question:15
Find the products:
-18
5
x
2
z ×
-25
6
xz
2
y
Solution:
= -
18
5
×
-25
6
× x
2
×x ×z ×z
2
×y = 15 ×x
(2+1)
×y ×z
(1+2)
= 15x
3
yz
3
Question:16
Find the products:
-3
14
xy
4
×
7
6
x
3
y
Solution:
=
-3
14
×
7
6
× x ×x
3
×y
4
×y =
-1
4
x
(1+3)
×y
(4+1)
=
-1
4
x
4
y
5
Question:17
Find the products:
-7
5
x
2
y ×
3
2
xy
2
×
-6
5
x
3
y
3
Solution:
=
-7
5
×
3
2
×
-6
5
× x
2
×x ×x
3
×y ×y
2
×y
3
=
63
25
×x
(2+1+3)
×y
(1+2+3)
=
63
25
x
6
y
6
Question:18
Find the products:
(2a
2
b) × (-5ab
2
c) × (-6bc
2
)
Solution:
= 2 × -5 × -6 × a
2
×a ×b ×b
2
×b ×c ×c
2
= 60 ×a
(2+1)
×b
(1+2+1)
×c
(1+2)
= 60a
3
b
4
c
3
Question:19
Find the products:
(-4x
2
) × (-6xy
2
) × (-3y)
( ) ( )
( ) ( )
( ) ( )
( ) ( )
( ) ( )
( ) ( )
( ) ( )
( ) ( )
( ) ( )
( ) ( )
( ) ( )
( ) ( ) ( )
( ) ( )
( ( ) ( ) ) ( )
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FAQs on RS Aggarwal Solutions: Algebraic Expressions - Mathematics (Maths) Class 7

1. What are algebraic expressions?
Ans. Algebraic expressions are mathematical expressions that contain variables, constants, and mathematical operations such as addition, subtraction, multiplication, and division. These expressions can be simplified or evaluated by substituting specific values for the variables.
2. How do you simplify algebraic expressions?
Ans. To simplify an algebraic expression, combine like terms by adding or subtracting them. Like terms have the same variables raised to the same powers. You can also simplify expressions by using the distributive property or applying the rules of exponents.
3. Can you provide an example of simplifying an algebraic expression?
Ans. Certainly! Let's simplify the expression 3x + 2y - 4x + 5y. To simplify, we combine the like terms: 3x - 4x + 2y + 5y = -x + 7y
4. How do you evaluate algebraic expressions?
Ans. To evaluate an algebraic expression, substitute specific values for the variables and perform the operations according to the given expression. Replace each variable with its corresponding value and simplify the expression to obtain a numerical result.
5. Can you provide an example of evaluating an algebraic expression?
Ans. Of course! Let's evaluate the expression 2x^2 - 3y + 4 for x = 3 and y = 2. Substituting the values, we get: 2(3)^2 - 3(2) + 4 = 18 - 6 + 4 = 16
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