Chapter 2: Polynomials

Overview

Curated Multiple Choice Questions (MCQ) worksheet on Class 10 Polynomials, covering zeroes of linear and quadratic polynomials, relationship between zeroes and coefficients, and graphical parabolas.

MCQ Worksheet

  1. Question 1: If one zero of the quadratic polynomial $x^2 + 3x + k$ is 2, then the value of $k$ is:
    (A) 10
    (B) -10
    (C) 5
    (D) -5
    Solution: (B) -10
    Since 2 is a zero, $p(2) = 0$.
    $(2)^2 + 3(2) + k = 0 \Rightarrow 4 + 6 + k = 0 \Rightarrow k = -10$.
  2. Question 2: A quadratic polynomial, whose zeroes are -3 and 4, is:
    (A) $x^2 - x + 12$
    (B) $x^2 + x + 12$
    (C) $x^2 - x - 12$
    (D) $2x^2 + 2x - 24$
    Solution: (C) $x^2 - x - 12$
    Sum of zeroes $= -3 + 4 = 1$. Product $= -3 \times 4 = -12$.
    Polynomial is $k[x^2 - (\text{Sum})x + \text{Product}] = k(x^2 - x - 12)$. For $k=1$, it is $x^2 - x - 12$.
  3. Question 3: The zeroes of the quadratic polynomial $x^2 + 99x + 127$ are:
    (A) both positive
    (B) both negative
    (C) one positive and one negative
    (D) both equal
    Solution: (B) both negative
    Since all coefficients are positive, both zeroes must be negative. (Sum is negative, Product is positive).
  4. Question 4: If the zeroes of the quadratic polynomial $x^2 + (a+1)x + b$ are 2 and -3, then:
    (A) $a = -7, b = -1$
    (B) $a = 5, b = -1$
    (C) $a = 2, b = -6$
    (D) $a = 0, b = -6$
    Solution: (D) $a = 0, b = -6$
    Sum $= 2 + (-3) = -1 = -(a+1) \Rightarrow a+1 = 1 \Rightarrow a=0$.
    Product $= 2(-3) = -6 = b$.
  5. Question 5: The number of polynomials having zeroes as -2 and 5 is:
    (A) 1
    (B) 2
    (C) 3
    (D) more than 3
    Solution: (D) more than 3
    There are infinite polynomials of the form $k(x+2)(x-5)$ where $k$ is any non-zero real number.
  6. Question 6: If one of the zeroes of the cubic polynomial $x^3 + ax^2 + bx + c$ is -1, then the product of the other two zeroes is:
    (A) $b - a + 1$
    (B) $b - a - 1$
    (C) $a - b + 1$
    (D) $a - b - 1$
    Solution: (A) $b - a + 1$
    Let zeroes be $\alpha, \beta, \gamma$ with $\alpha = -1$.
    $P(-1) = -1 + a - b + c = 0 \Rightarrow c = 1 - a + b$.
    Product $\alpha\beta\gamma = -c \Rightarrow (-1)\beta\gamma = -c \Rightarrow \beta\gamma = c = 1 - a + b$.
  7. Question 7: The zeroes of the quadratic polynomial $x^2 + kx + k, k \neq 0$,
    (A) cannot both be positive
    (B) cannot both be negative
    (C) are always unequal
    (D) are always equal
    Solution: (A) cannot both be positive
    For real roots, $D = k^2 - 4k \ge 0 \Rightarrow k(k-4) \ge 0$. So $k<0$ or $k \ge 4$.
    If $k \ge 4$, sum ($-k$) is negative and product ($k$) is positive $\Rightarrow$ both negative.
    If $k < 0$, sum is positive and product is negative $\Rightarrow$ one positive, one negative.
    In neither case can both be positive.
  8. Question 8: If the zeroes of the quadratic polynomial $ax^2 + bx + c, c \neq 0$ are equal, then:
    (A) c and a have opposite signs
    (B) c and b have opposite signs
    (C) c and a have the same sign
    (D) c and b have the same sign
    Solution: (C) c and a have the same sign
    For equal roots, $D = b^2 - 4ac = 0 \Rightarrow b^2 = 4ac$. Since $b^2 > 0$, $4ac$ must be positive, which implies $a$ and $c$ must have the same sign.
  9. Question 9: If one of the zeroes of a quadratic polynomial of the form $x^2 + ax + b$ is the negative of the other, then it:
    (A) has no linear term and the constant term is negative.
    (B) has no linear term and the constant term is positive.
    (C) can have a linear term but the constant term is negative.
    (D) can have a linear term but the constant term is positive.
    Solution: (A) has no linear term and the constant term is negative.
    Zeroes are $\alpha, -\alpha$. Sum $= 0 = -a \Rightarrow a=0$ (no linear term).
    Product $= -\alpha^2 = b$. Since $\alpha^2 > 0$, $b$ is negative.
  10. Question 10: Which of the following is not the graph of a quadratic polynomial?
    (A) Parabola opening up
    (B) Parabola opening down
    (C) Parabola cutting x-axis at 2 points
    (D) S-shaped curve
    Solution: (D) S-shaped curve
    The graph of a quadratic polynomial is always a parabola. An S-shaped curve typically represents a cubic polynomial.
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