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All questions of Polynomials for EmSAT Achieve Exam

Can you explain the answer of this question below:
 If α and β are the zeroes of the polynomial 5x2 – 7x + 2, then sum of their reciprocals is:
  • A:
    14/25
  • B:
    7/5
  • C:
    2/5
  • D:
    7/2
The answer is d.

Anshu Shah answered
We have 2 find (1/α + 1/β)
now 1/α + 1/β = (α + β)/ α β (taking LCM)
now by the given poly. we get
(α + β) = -b/a = 7/5
α β = c/a = 2/5
so, (α + β)/ α β = (7/5) / (2/5)
= 7/2
So, 1/α + 1/β = (α + β)/ α β = 7/2
Hence, 1/α + 1/β = 7/2

If p and q are the zeroes of the polynomial x2- 5x + k. Such that p - q = 1, find the value of K
  • a)
    6
  • b)
    7
  • c)
    8
  • d)
    9
Correct answer is option 'A'. Can you explain this answer?

Zachary Foster answered
Given α and β are the zeroes of the polynomial x− 5x + k
Also given that α − β = 1 → (1)
Recall that sum of roots (α + β) = −(b/a)
∴ α + β = 5 → (2)
Add (1) and (2), we get
α − β = 1
α + β = 5
2α = 6
∴ α = 3
Put α = 3 in α + β = 5
3 + β = 5
∴ β = 2
Hence 3 and 2 are zeroes of the given polynomial
Put x = 2 in the given polynomial to find the value of k ( Since 2 is a zero of the polynomial, f(2) will be 0 )

x− 5x + k = 0
⇒ 2− 5(2) + k = 0
⇒ 4 − 10 + k = 0
⇒ − 6 + k = 0
∴ k = 6

 The three zeroes of the polynomial 2x3 + 5x2 – 28x – 15 _____
  • a)
    All three are not real numbers
  • b)
    Are all Natural numbers
  • c)
    Are all rational numbers
  • d)
    Are all Integers
Correct answer is option 'C'. Can you explain this answer?

Gaurav Kumar answered
Since the solution is not a complex number, it is a real number. Since rational numbers include all integers, natural numbers and fractions , So the numbers are rational numbers.

If α,β be the zeros of the quadratic polynomial 2 – 3x – x2, then α + β =
  • a)
    2
  • b)
    3
  • c)
    1
  • d)
    None of these
Correct answer is option 'D'. Can you explain this answer?

Pooja Shah answered
If α  and β are the zeros of the polynomial then
(x−α)(x−β) are the factors of the polynomial
Thus, (x−α)(x−β) is the polynomial.
So, the polynomial =x− αx − βx + αβ
=x− (α + β)x + αβ....(i) 
Now,the quadratic polynomial is  
2 − 3x − x2 = x2 + 3x − 2....(ii)
Now, comparing equation (i) and (ii),we get,
−(α + β) = 3 
α + β = −3

 What value/s can x take in the expression k(x – 10) (x + 10) =0 where k is any real number.
  • a)
    100, -100
  • b)
    Infinitely many
  • c)
    Depends on value of k
  • d)
    10, -10
Correct answer is option 'D'. Can you explain this answer?

Avinash Patel answered
k(x – 10) (x + 10) =0
⇒ either k=0
Or x-10=0
Or x+10=0
Since we don’t know the value of k 
So either x-10=0
x=10
Or x+10=0
x=-10
So values of x can be 10,-10

 If “1” is a zero of the polynomial P(a) = x2a2 – 2xa + 3x – 2 , then x = ______
  • a)
    2
  • b)
    -2, 1
  • c)
    +2, -2
  • d)
    -2, 0
Correct answer is option 'B'. Can you explain this answer?

Pooja Shah answered
The correct solution of this question is given below:
Here, P(a) = x2a2 - 2xa + 3x - 2
1 is a zero of P(a), so P(1) = 0
Therefore, x212 - 2x.1 + 3x - 2 = 0
x2 + x - 2 = 0
(x + 2)(x - 1) = 0
x = -2, 1

A polynomial of degree three is called ……
  • a)
    cubic polynomial
  • b)
    quadratic polynomial
  • c)
    linear polynomial
  • d)
    zero polynomial
Correct answer is option 'A'. Can you explain this answer?

cubic polynomial is a polynomial of the form . A cubic polynomial is a polynomial of degree 3. A univariate cubic polynomial has the form . An equation involving a cubic polynomial is called a cubic equation. A closed-form solution known as the cubic formula exists for the solutions of an arbitrary cubic equation.

If (x + 1) is a factor of x2 – 3ax + 3a – 7, then the value of a is
  • a)
    -2
  • b)
    0
  • c)
    1
  • d)
    -1
Correct answer is option 'C'. Can you explain this answer?

Anjana Khatri answered
Since (X+1) is a factor of x^2 - 3ax + 3a - 7 

Therefore , x + 1 = 0

or, x=-1

Putting the value of x in the the p(x) = x^2 - 3ax + 3a - 7 

or, (-1)^2 - 3(a)(-1) + 3a - 7 = 0
 
1+3a+3a-7=0

6a=6

or, a=1

Therefore, the  value of a = 1.

Can you explain the answer of this question below:

If (x + 1) is a factor of 2x3 + ax2 + 2bx + 1, then find the values of a and b given that 2a – 3b = 4.​

  • A:

    a = 2, b = 2

  • B:

    a = 5, b = 5

  • C:

    a = 2, b = 5

  • D:

    a = 5, b = 2

The answer is d.

Vikram Kapoor answered
Given is the value of a and b. 

given that (x+1) is a factor of p(x) 

therefore, -1 is a zero of given p(x) 

p(x) = 2x3 +ax2 +2bx +1

 substituting the value of -1 in the given p(x), we get

 p(x)=2*(-1)3 +a *(-1)2 +2*b*(-1)+ 1

 = -2 + a -2b + 1 

= -1 + a - 2b

 or,a - 2b = 1 

also given that 2a - 3b = 4 

so we got two equations; 

a - 2b = 7 ...(1)

 2a - 3b = 4 ...(2) 
(1)* (2)* (4)- 2 = 2a - 4b = (3)

(2)* 1 = 2a - 3b = 4 (4) 

(4) -  (3) = [2a - 2a ] + [-3b - (-4b)] = 4 - 2

-3b + 4b = 2

therefore b = 2 

substituting the value of bin (3)

2a - 4b = 2

2a - (4*2) = 2

2a - 8 = 2

2a = 2 + 8

2 = 10

a = 10 / 2

therefore a = 5 

so we get the value of a and b 

that is ; a = 5 and b = 2

If x = 2 and x = 3 are zeros of the quadratic polynomial x2 + ax + b, the values of a and b respectively are :
  • a)
    5, 6
  • b)
    - 5, - 6
  • c)
    - 5, 6
  • d)
    5, - 6
Correct answer is option 'C'. Can you explain this answer?

Gaurav Kumar answered
Zeros of the polynomials are the values which gives zero when their value is substituted in the polynomial
When x=2,
x2+ax+b =(2)2+a*2+b=0
4+2a+b=0
b=-4-2a    ….1
When x=3,
(3)2+ 3a + b=0
9 + 3a + b=0
Substituting 
9 + 3a - 4 - 2a =0
5 + a =0
a = -5
b = 6

Find the quadratic polynomial whose zeros are 2 and -6
  • a)
    x2 + 4x + 12
  • b)
    x2 – 4x – 12
  • c)
    x2 + 4x – 12
  • d)
    x2 – 4x + 12
Correct answer is option 'C'. Can you explain this answer?

Naina Sharma answered
We know that quadratic equation is of the form x2-(sum of zeros)x+product of zeros
Sum of zeros=2-6=-4
Product of zeros=2*(-6)=-12
x2-(sum of roots )x + product of roots
x2-(-4)x + 12
x2+4x-12
So the equation is x2+4x-12

The value of 155 mod 9 is
  • a)
    0
  • b)
    1
  • c)
    2
  • d)
    3
Correct answer is option 'C'. Can you explain this answer?

Raghav Bansal answered
By the Division algorithm 155 = 9(17) + 2. Where remainder is 155 mod 9.

 If two zeroes of a polynomial 4x4 -20x3 +23 x2 + 5x – 6 are ½ and – ½ , the how many more zeroes does it have?
  • a)
    3
  • b)
    None
  • c)
    1
  • d)
    2
Correct answer is option 'D'. Can you explain this answer?

Krishna Iyer answered
The polynomial with degree 4 is a biquadratic equation. And a polynomial has no. of zeros equal to the degree of the polynomial. So total no. of zeros are 4. 2 zeros are already provided to us , so it has 2 more zeros.

Can you explain the answer of this question below:

 When x2 – 2x + k divides the polynomial x4 – 6x3 + 16x2 – 25x + 10, the remainder is (x + a) . The value of a is _________

  • A:

    -3

  • B:

    3

  • C:

    -5

  • D:

    5

The answer is c.

Pooja Shah answered
Given that the remainder is (x + a)
⇒ (4k – 25 + 16 – 2k)x + [10 – k(8 – k) ] = x + a  
⇒ (2k – 9)x + [10 – 8k + k2 ] = x + a
On comparing both the sides, we get
2k  – 9 = 1
⇒ 2k = 10
∴ k = 5
Also 10 – 8k + k2 = a
⇒ 10 – 8(5) + 52 = a
⇒ 10 – 40 + 25 = a
∴ a = – 5

The value of p when x3 + 9x2 + px – 10 is exactly divisible by (x+ 2 ) is ____
  • a)
    1
  • b)
    9
  • c)
    3
  • d)
    6
Correct answer is option 'B'. Can you explain this answer?

Trisha das answered
Solution:

To find the value of p that makes x^3 + 9x^2 + px + 10 exactly divisible by (x + 2), we can use the remainder theorem.

The remainder theorem states that if a polynomial f(x) is divided by (x - a), then the remainder is f(a).

Therefore, if we divide x^3 + 9x^2 + px + 10 by (x + 2), the remainder will be equal to f(-2), where f(x) = x^3 + 9x^2 + px + 10.

We can find f(-2) by substituting -2 for x in the expression for f(x):

f(-2) = (-2)^3 + 9(-2)^2 + p(-2) + 10
= -8 + 36 - 2p + 10
= 18 - 2p

Since we want the remainder to be zero (i.e. we want (x + 2) to be a factor of x^3 + 9x^2 + px + 10), we must have:

18 - 2p = 0

Solving for p, we get:

p = 9

Therefore, the value of p that makes x^3 + 9x^2 + px + 10 exactly divisible by (x + 2) is 9.

 Find the sum and the product of the zeroes of the polynomial: x2-3x-10​
  • a)
    3, 10
  • b)
    -3, -10
  • c)
    3,-10
  • d)
    -3, 10
Correct answer is option 'C'. Can you explain this answer?

Raghav Bansal answered
X²-3x-10

x² -(5x-2x)-10

x² - 5x+2x-10

x(x-5)+2(x-5)

(x-5)(x+2)

x=5

x=-2

Sum of zeroes = α+β = 5-2 = 3
α+β = -b/a = -(-3)/1 = 3

Product of zeroes = αβ = 5*-2 = -10

αβ = c/a = -10/1 = -10

If the degree of the dividend is 5 and the degree of the divisor is 3, then the degree of the quotient will be
  • a)
    2
  • b)
    1
  • c)
    -2
  • d)
    0
Correct answer is option 'A'. Can you explain this answer?

Vikas Kumar answered
The degree of the dividend is 5 and that of the divisor is 3;Therefore, if expression with degree 5 is divided by expression with degree 3, then the degree of the quotient is 2.

The number of polynomials having zeroes -2 and 5 is:
  • a)
    1
  • b)
    3
  • c)
    2
  • d)
    more than 3
Correct answer is option 'D'. Can you explain this answer?

Amit Kumar answered
Since the question doesn’t say that there are only 2 zeros of the polynomial we , there can be n number of polynomials which have two of its zeros as -2 and 5 .So the correct answer is more than 3.

The expression that should be subtracted from the polynomial f(x) = x4 + 2x3-13x2 – 12x + 21 so that the resulting polynomial is exactly divisible by g(x) = x2 – 4x + 3 is​
  • a)
    x2 – 3
  • b)
    2x – 3
  • c)
    x – 4
  • d)
    x2 + 4
Correct answer is option 'B'. Can you explain this answer?

Rahul Kapoor answered
Any division statement can be rewritten in the form of
Dividend = Divisor x Quotient + Remainder.
When the remainder is zero, the dividend is said to be the multiple of the divisor.
 
When the remainder is not equal to zero, and if it is subtracted from the dividend, then the dividend would become a multiple of divisor.
 
Dividend = x^4+2x^3-13x^2-12x+21
Divisor = x^2-4x+3
Step 1: Divide the dividend by divisor

Quotient = x^2+6x+8
Remainder = 2x – 3
 
Step 2: Hence, on subtracting 2x – 3 from the dividend, it will be exactly divisible by the given divisor.
 
Verification:
On subtracting 2x – 3 from the dividend, we get
x^4+2x^3-13x^2-12x+21-(2x-3) = x^4+2x^3-13x^2-14x+24
Dividing x^4+2x^3-13x^2-14x+24 by x^2-4x+3

Quotient = x^2+6x+8
Remainder = 0

 If the point (5,0) , (0-2) and (3,6) lie on the graph of a polynomial . Then which of the following is a zero of the polynomial?
  • a)
    5
  • b)
    6
  • c)
    not defined
  • d)
    -2
Correct answer is option 'A'. Can you explain this answer?

Sanaya sharma answered
Explanation:
Since, a zero of a polynomial always lies on the x-axis as a point. In the given question the point (5,0) is a point that lies on x-axis, so its corresponding x value represents zero of the polynomial.
Therefore, 5 is the zero of the polynomial. 
Hence, the correct option is A.
You can know more about Geometrical Meaning of the Zeroes of a Polynomial through the document: 

The quadratic polynomial whose sum of zeroes is 3 and product of zeroes is –2 is :
  • a)
     x2 + 3x – 2
  • b)
    x2 – 2x + 3
  • c)
    x2 – 3x + 2
  • d)
    x2 – 3x – 2
Correct answer is 'C'. Can you explain this answer?

Pooja Shah answered
Sum of zeros = 3/1
-b/a = 3/1
Product of zeros = 2/1
c/a = 2/1
This gives 
a = 1
b = -3
c = -2,
The required quadratic equation is
ax2+bx+c
So,  x2-3x+2

If sum of the squares of zeros of the quadratic polynomial f(x) = x2 – 8x + k is 40, find the value of k.​
  • a)
    12
  • b)
    -12
  • c)
    14
  • d)
    -14
Correct answer is option 'A'. Can you explain this answer?

Shantala nair answered
p (x)= x^2-8x+k
p (x)=Ax^2+Bx+C(The equation is in this form)
Let the zeroes be 'a' and 'b'
It is given that 
=> a^2+b^2=40
=> (a+b)^2 - 2ab = 40 ----1
sum of zeroes
=> a+b = -B/A = -(-8)/1 = 8
Product of zeroes 
=> a*b = C/A  = k
Substitute these values in the equation1 we get
=> 8^2 - 2k = 40
=> 64 - 2k = 40
=> 2k = 24
=> k = 12
Therefore the value of k is 12

If -√5 and √5 are the roots of the quadratic polynomial. Find the quadratic polynomial.
  • a)
    x-5
  • b)
    (x-5)(x+5)
  • c)
    x2 – 5
  • d)
    x2 – 25
Correct answer is option 'C'. Can you explain this answer?

Vikram Kapoor answered
We have as the roots which means x + and x- are the factors of the quadratic equation. Multiplying x+ and x- and applying a2-bwe get the equation x2-5.

If one zero of 2x2 – 3x + k is reciprocal to the other, then the value of k is :​
  • a)
    2
  • b)
    -2/3
  • c)
    -3
  • d)
    -3/2
Correct answer is option 'A'. Can you explain this answer?

Rajiv Gupta answered
Given: 2x^2-3x+k ....eq 1

Let the 2 zeroes be α & 1/α

Quadratic form : ax^2+bx+c....eq 2

On comparing eq 1 & eq 2 we get

a=2 ,b = -3, c= k

Product of zeroes = α x 1/α = 1

Product of zeroes= c/a

1= k/ 2 

K= 2

The value of k is 2.

Sum and the product of zeroes of the polynomial x2 +7x +10 is 
  • a)
    10/7 and -10/7
  • b)
    7/10 and -7/10
  • c)
    -7 and 10
  • d)
    7 and -10
Correct answer is option 'C'. Can you explain this answer?

Ananya Das answered
x2 + 7x + 10 = (x + 2)(x + 5)
So, the value of x2 + 7x + 10 is zero when x + 2 = 0 or x + 5 = 0
Therefore, the zeroes of x2 + 7x + 10 are –2 and –5.
Sum of zeroes = -7 = –(Coefficient of x) / (Coefficient of x2)
Product of zeroes = 10 = Constant term / Coefficient of x2

If α,β be the zeros of the quadratic polynomial 2x2 + 5x + 1, then value of α + β + αβ =
  • a)
    - 2
  • b)
    - 1
  • c)
    1
  • d)
    None of these
Correct answer is option 'A'. Can you explain this answer?

Naina Sharma answered
P(x) = 2x² + 5x + 1
Sum of roots = -5/2
Product of roots = 1/2
Therefore substituting these values, 
α + β +αβ 
=(α + β) + αβ
= -5/2 + 1/2
= -4/2 
= -2

Find the sum and the product of zeroes of the polynomial x2 +7x +10
  • a)
    7,-10
  • b)
    7, 10
  • c)
    -7,-10
  • d)
    -7, 10
Correct answer is option 'D'. Can you explain this answer?

x2 + 7x + 10 = (x + 2)(x + 5)
So, the value of x2 + 7x + 10 is zero when x + 2 = 0 or x + 5 = 0
Therefore, the zeroes of x2 + 7x + 10 are –2 and –5.
Sum of zeroes = -7 = –(Coefficient of x) / (Coefficient of x2)
Product of zeroes = 10 = Constant term / Coefficient of x2

 If α and β are the zeroes of the polynomial 5x2 – 7x + 2, then sum of their reciprocals is:
  • a)
    14/25
  • b)
    7/5
  • c)
    2/5
  • d)
    7/2
Correct answer is 'D'. Can you explain this answer?

We have 2 find (1/α + 1/β)
now 1/α + 1/β = (α + β)/ α β (taking LCM)
now by the given poly. we get
(α + β) = -b/a = 7/5
α β = c/a = 2/5
so, (α + β)/ α β = (7/5) / (2/5)
= 7/2
So, 1/α + 1/β = (α + β)/ α β = 7/2
Hence, 1/α + 1/β = 7/2

Assertion (A): A polynomial of degree n cannot have more than n terms.
Reason (R): The number of coefficients in a polynomial is always one more than its degree.
  • a)
    Both Assertion and Reason are correct, and Reason is the correct explanation of Assertion.
  • b)
    Both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
  • c)
    The assertion is correct, but the Reason is incorrect.
  • d)
    Assertion is incorrect, but Reason is correct.
Correct answer is option 'D'. Can you explain this answer?

Khusboo shah answered
Understanding the Assertion and Reason
The assertion (A) states that a polynomial of degree n cannot have more than n terms. The reason (R) states that the number of coefficients in a polynomial is always one more than its degree. Let's break down these statements.
Assertion (A): Analysis
- A polynomial of degree n is defined as a mathematical expression of the form:
- a_n * x^n + a_(n-1) * x^(n-1) + ... + a_1 * x + a_0
- The degree of a polynomial is determined by the highest power of the variable x.
- A polynomial can indeed have fewer than n terms (e.g., x^n + x^2 has 2 terms but is still degree n).
- Therefore, the assertion is incorrect as a polynomial can have more than n terms, as long as terms are combined appropriately.
Reason (R): Analysis
- The reason correctly states that the number of coefficients in a polynomial is always one more than its degree.
- This is because each term has a coefficient, including the constant term (a_0).
- For example, a polynomial of degree 3 (like x^3 + 2x^2 + 3x + 4) has 4 coefficients (a_3, a_2, a_1, and a_0).
Conclusion
- The assertion is incorrect, but the reason is correct.
- Thus, the correct option is D: Assertion is incorrect, but Reason is correct.
This analysis highlights the importance of understanding polynomials and their properties in mathematics.

The sum and product of zeros of the quadratic polynomial are – 5 and 3 respectively the quadratic polynomial is equal to –
  • a)
    x2 + 2x + 3
  • b)
    x2 – 5x + 3
  • c)
    x2 + 5x + 3
  • d)
    x2 + 3x – 5
Correct answer is option 'C'. Can you explain this answer?

If α, β  be the zeros of the quadratic polynomial ,then
(x−α)(x−β) is the quadratic polynomial.
Thus, (x−α)(x−β) is the polynomial.
=x^2−αx−βx+αβ
=x^2−x(α+β)+αβ(i) 
(α+β)=−5αβ=3
Now putting the value of (α+β),αβ in equation (i) we get,
x^2−x(−5)+3
=x^2+5x+3

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