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10th Grade > Mathematics

POLYNOMIALS MCQs

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Total Questions : 79 | Page 8 of 8 pages
Question 71.


If α,β and γ are the zeroes of the polynomial f(x)=ax3+bx2+cx+d, then 1α+1β+1γ is _____.


  1.     cd
  2.     ad
  3.     cd
  4.     ba
 Discuss Question
Answer: Option C. -> cd
:
C

Given α,β and γ are the zeroes of the polynomial f(x)=ax3+bx2+cx+d
1α+1β+1γ
=βγ+αγ+αβ(αβγ) =(ca)(da) =cd


Question 72.


When 3x3+2x2x+4 is divided by 3+2x the remainder is 18.


  1.     True
  2.     False
  3.     cd
  4.     ba
 Discuss Question
Answer: Option A. -> True
:
A
P(x)=3x3+2x2x+4
If P(x) is divided by (xa), then the remainder is P(a)
2x+3=0x=32
So, the  remainder is the value of polynomial at 32
Substituting x=32 in p(x)
p(32)=3(32)3+2(32)2(32)+4
 p(32)=3(278)+2(94)(32)+4
p(32)=818+92+32+4
p(32)=81+36+12+328
p(32)=81+808
p(32)=18
The remainder is 18.
Thus, the given statement is true.
Question 73.


What will be the remainder when 4x43x3+2x2x is divided by x+1?


  1.     1
  2.     0
  3.     7
  4.     10
 Discuss Question
Answer: Option D. -> 10
:
D

Given p(x)=4x43x3+2x2x
To find the remainder of  4x43x3+2x2xx+1,
we will use remainder theorem.
Remainder of p(x)xa is p(a).
Remainder of  4x43x3+2x2xx+1 is p(1).


[x+1=x(1)]


p(1)=4(1)43(1)3+2(1)2(1)
p(1)=4+3+2+1=10


Hence, the remainder of 4x43x3+2x2xx+1 is 10.


Question 74.


If 1 is a zero of the polynomial p(x), then which of the following is correct?


  1.     p(1) = x
  2.     p(1) = 0
  3.     p(1) = 1
  4.     p(2) - p(1) = p(2)
 Discuss Question
Answer: Option B. -> p(1) = 0
:
B and D

If k is a zero of the polynomial p(x), then, p(k)=0.
 
Here, 1 is a zero of the polynomial p(x).
p(1)=0
Also, p(2)p(1)=p(2)0=p(2)


Question 75.


Which of the following graph represents a quadratic polynomial which has sum of its zeroes is zero?


  1.     A)image
  2.     B)image
  3.     C)image
  4.     D)image
 Discuss Question
Answer: Option D. -> D)image
:
D

We know that, the values at which a quadratic polynomial cuts the x-axis are its zeroes.
Option A: Polynomial cuts the x-axis at : -3, -2 ; sum of zeroes: -5
Option B: Polynomial cuts the x-axis at : 2, 3; sum of zeroes: 5
Option C: Polynomial cuts the x-axis at : 2, 3; sum of zeroes: 5
Option D: Polynomial cuts the x-axis at : -2, 2; sum of zeros: 0 
Hence, the answer is D.


Question 76.


The zeroes of mn(x2+1)=(m2+n2)x are:


  1.     mn and nm
  2.     mn and nm
  3.     mn and nm
  4.     mn and nm
 Discuss Question
Answer: Option A. -> mn and nm
:
A
Given polynomial, mn(x2+1)=(m2+n2)x
Let's factorise it.
mnx2(m2+n2)x+mn=0
mnx2m2xn2x+mn=0
mx(nxm)n(nxm)=0
(mxn)(nxm)=0
mxn=0 or nxm=0
x=mn or nm
So, zeroes of the given polynomial are mn and nm.
Question 77.


If α,β are the zeroes of the polynomial x2px+36 and α2+β2 = 9, then what is the value of p?


  1.     ±6
  2.     ±3
  3.     ±8
  4.     ±9    
 Discuss Question
Answer: Option D. -> ±9    
:
D

Given polynomial x2px+36
On comparing with the standard form of a quadratic polynomial ax2+bx+c, we get
a = 1, b = -p, c = 36
Here, α and β are the zeroes of  the polynomial.
α+β=ba=p
and αβ=ca=36
Now, α2+β2=(α+β)2 - 2αβ
 9=p22×36  [α2+β2 = 9]
81=p2
p=9  or 9


Question 78.


Which of the following graph represents the quadratic polynomial x2+5x6?


  1.     image
  2.     image
  3.     image
  4.     None of the above
 Discuss Question
Answer: Option C. -> image
:
C
One way of solving this question is to find the zeroes of given polynomial by conventional factorization. But we will solve it in a smart way. We just find the sum of zeroes from polynomial and compare it from the graphs, which satisfies the sum of zeroes.
From polynomial,
Sum of zeroes = ba = 51 = 5
From the graphs given , we look for graph whose sum of zeroes is 5. Thus graph having 2,3 as zeroes is the required graph.
Question 79.


Graph of a quadratic polynomial is a 


  1.     straight line 
  2.     circle
  3.     parabola
  4.     ellipse
 Discuss Question
Answer: Option C. -> parabola
:
C
Quadratic polynomial is of degree 2 and the graph of a quadratic polynomial is parabola.

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