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CBSE 10th Maths - Polynomials - MCQ's

58785.The zeroes of $x^2$–2x –8 are:
(2,-4)
(4,-2)
(-2,-2)
(-4,-4)
Explanation:

Explanation: $x^2$–2x –8 = $x^2$–4x + 2x –8

= x(x–4)+2(x–4)

= (x-4)(x+2)

Therefore, x = 4, -2.

58786.If the zeroes of the quadratic polynomial $ax^2+bx+c$, c≠0 are equal, then
c and b have opposite signs
c and a have opposite signs
c and b have same signs
c and a have same signs
Explanation:

For equal roots, discriminant will be equal to zero.

$b^2$ -4ac = 0

$b^2$ = 4ac

ac = $\dfrac{b^2}{4}$

ac>0 (as square of any number cannot be negative)

58787.The degree of the polynomial, $x^4 – x^2 +2$ is
2
4
1
0
Explanation:

Degree is the highest power of the variable in any polynomial.

58788.If p(x) is a polynomial of degree one and p(a) = 0, then a is said to be:
Zero of p(x)
Value of p(x)
Constant of p(x)
None of the above
Explanation:

Let p(x) = mx+n

Put x = a

p(a)=ma+n=0

So, a is zero of p(x).

58789.Zeroes of a polynomial can be expressed graphically. Number of zeroes of polynomial is equal to number of points where the graph of polynomial is:
Intersects x-axis
Intersects y-axis
Intersects y-axis or x-axis
None of the above
58790.Given that two of the zeroes of the cubic polynomial $ax^3 + bx^2 + cx + d$ are 0, the third zero is
$\dfrac{-b}{a}$
$\dfrac{b}{a}$
$\dfrac{c}{a}$
$\dfrac{-d}{a}$
Explanation:

Let α be the third zero.

Given that two zeroes of the cubic polynomial are 0.

Sum of the zeroes = α + 0 + 0 = $\dfrac{-b}{a}$

α = $\dfrac{-b}{a}$

58791.If one zero of the quadratic polynomial $x^2 + 3x + k$ is 2, then the value of k is
10
–10
5
–5
Explanation:

Given that 2 is the zero of the quadratic polynomial $x^2 + 3x + k.$

$(2)^2$ + 3(2) + k = 0

4 + 6 + k = 0

k = -10

58792.The zeroes of the quadratic polynomial $x^2 + 7x + 10$ are
-4, -3
2, 5
-2, -5
-2, 5
Explanation:

$x^2$ + 7x + 10 = $x^2$ + 2x + 5x + 10

= x(x + 2) + 5(x + 2)

= (x + 2)(x + 5)

Therefore, -2 and -5 are the zeroes of the given polynomial.

58793.By division algorithm of polynomials, p(x) =
g(x) × q(x) + r(x)
g(x) × q(x) – r(x)
g(x) × q(x) × r(x)
g(x) + q(x) + r(x)
Explanation:

By division algorithm of polynomials, p(x) = g(x) × q(x) + r(x).

58794.The product of the zeroes of the cubic polynomial $ax^3 + bx^2 + cx + d$ is
$\dfrac{-b}{a}$
$\dfrac{c}{a}$
$\dfrac{-d}{a}$
$\dfrac{-c}{a}$
Explanation:

The product of the zeroes of the cubic polynomial $ax^3 + bx^2 + cx + d$ is $\dfrac{-d}{a}$

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