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Q1. A student observes that the graph of y = 2x + 3 crosses the x-axis at x = −3/2. Which statement best explains why this x-value is called a zero of the polynomial 2x + 3?
Answer: A — A zero is defined as a value of x where p(x) = 0, not merely where the graph intersects the x-axis; option B describes the geometric consequence but not the algebraic definition, which is what 'zero' means.
Q2. Assertion (A): A quadratic polynomial ax² + bx + c with a > 0 can have no real zeroes. Reason (R): When the parabola y = ax² + bx + c opens upward and does not intersect the x-axis, the polynomial has no real zeroes. Choose the correct option:
Answer: A — Both statements are true; R directly explains why A is true because the geometric fact (no x-intercept) is the reason the algebraic fact (no real zeroes) holds.
Q3. A linear polynomial p(x) = ax + b has exactly one zero at x = k. Which of the following must be true?
Answer: B — If k is a zero, then p(k) = 0, which means the point (k, 0) satisfies the equation y = ax + b; a horizontal line would have infinitely many zeroes or none, and b and a have no fixed sign restrictions.
Q4. Consider two quadratic polynomials: p(x) = x² − 5x + 6 and q(x) = −x² + 5x − 6. A student claims that p(x) and q(x) have the same zeroes because one is the negative of the other. Is this claim always true, sometimes true, or never true?
Answer: D — If p(k) = 0, then −p(k) = 0 as well, so q(k) = −p(k) = 0; the zeroes are identical, not opposite (verify: p(x) = 0 at x = 2, 3; q(x) = 0 also at x = 2, 3).
Q5. Assertion (A): A cubic polynomial ax³ + bx² + cx + d always has at least one real zero. Reason (R): A cubic polynomial has degree 3, which is odd, so its graph must cross the x-axis at least once. Choose the correct option:
Answer: A — Both are true; the odd degree ensures the polynomial takes both positive and negative values, so by continuity it must cross the x-axis, which is exactly why it has at least one real zero.
Q6. A quadratic polynomial has zeroes at x = 2 and x = 5. Which statement correctly relates the zeroes to the polynomial's properties?
Answer: A — Any quadratic with zeroes 2 and 5 can be written as a(x − 2)(x − 5), where a ≠ 0 is arbitrary; option B fixes a = 1, option C requires a > 0, and option D requires 10a > 0, all of which are unnecessary restrictions.
Q7. Assertion (A): If p(x) is a polynomial and p(k) = 0, then (x − k) is a factor of p(x). Reason (R): The zero of a linear polynomial ax + b is always x = −b/a. Choose the correct option:
Answer: B — Both are true statements, but R is about linear polynomials only and does not explain A, which is a general statement about any polynomial; A is known as the Factor Theorem.
Q8. A student graphs y = x² − 4 and observes it crosses the x-axis at x = −2 and x = 2. Based on this observation, which algebraic fact does the student verify?
Answer: A — The x-intercepts directly verify that p(−2) = 0 and p(2) = 0, which is the definition of zeroes; while B, C, and D are related properties, they are not directly verified by observing where the graph crosses the x-axis.
Q9. Assertion (A): Every polynomial of degree n has at most n zeroes. Reason (R): A polynomial can be written as a product of linear factors corresponding to its zeroes. Choose the correct option:
Answer: B — Both statements are true, but R describes factorization while A is a statement about the maximum count of zeroes; R is related but does not fully explain why the maximum is exactly n (the explanation requires the Fundamental Theorem of Algebra).
Q10. A polynomial p(x) has the property that p(0) = 5. Based solely on this information, which conclusion is valid?
Answer: B — p(0) gives the y-intercept, which equals the constant term; p(0) = 5 tells us nothing about whether 5 is a zero (it is not, since p(5) is unknown), the degree, or the existence of other zeroes.
What is the definition of a zero of polynomial p(x)?
A real number k is a zero of p(x) if p(k) = 0.
What is the general form of a quadratic polynomial?
ax² + bx + c, where a, b, c are real numbers and a ≠ 0.
How many zeroes can a quadratic polynomial have at most?
A quadratic polynomial can have at most 2 zeroes.
What does a zero of a polynomial represent on its graph?
A zero of p(x) is the x-coordinate of the point where the graph intersects the x-axis.
If p(x) = 2x + 3, what is its zero?
The zero is -3/2, found by solving 2x + 3 = 0.
What is the shape of the graph of a quadratic polynomial ax² + bx + c when a > 0?
The parabola opens upwards.
What is the difference between a cubic polynomial and a quadratic polynomial?
A cubic polynomial has degree 3, while a quadratic has degree 2; a cubic can have up to 3 zeroes.
When does a quadratic polynomial have exactly one zero?
When the parabola touches the x-axis at exactly one point (two coincident zeroes).
For linear polynomial ax + b (a ≠ 0), what is the zero?
The zero is -b/a, which equals -(Constant term)/(Coefficient of x).
Can a quadratic polynomial have no real zeroes? If yes, what does this mean graphically?
Yes; the parabola is completely above or below the x-axis and never intersects it.
Define the zero of a polynomial. Is –2 a zero of the polynomial p(x) = 3x² + 5x – 2? Justify your answer. [2 marks]
Zero is defined as k where p(k) = 0. Calculate p(–2) = 3(4) + 5(–2) – 2 and check if it equals zero.
Find the zeroes of the quadratic polynomial x² – 2x – 8 and verify that they are the x-coordinates of the points where the graph intersects the x-axis. [3 marks]
Factor x² – 2x – 8 = (x – 4)(x + 2) to find zeroes 4 and –2. Verify by substituting: p(4) = 0 and p(–2) = 0; these x-values are where the parabola touches the x-axis.
Explain with the help of a graph why a quadratic polynomial can have 0, 1, or 2 zeroes. How does the position of the parabola relative to the x-axis determine the number of zeroes? Also, state how many zeroes a cubic polynomial can have at most. [5 marks]
Describe three cases: (1) parabola cuts x-axis at two points → 2 distinct zeroes; (2) parabola touches x-axis at one point → 1 zero (repeated); (3) parabola lies completely above/below x-axis → no zeroes. Explain that 'a' (coefficient of x²) determines if parabola opens up/down. A cubic polynomial of degree 3 has at most 3 zeroes by the fundamental theorem.
Q1. Assertion (A):
A polynomial of degree 2 is called a quadratic polynomial and has the general form ax² + bx + c where a ≠ 0.
Reason (R):
A quadratic polynomial must have its highest power equal to 2, and the coefficient of x² cannot be zero.
Answer: A — Both A and R are true, and R is the correct explanation of A — Both the assertion and reason are true. The assertion correctly defines a quadratic polynomial with the standard form. The reason is the correct explanation because it explains why 'a ≠ 0' is required (to ensure the highest power is actually 2, not less). This is a fundamental definition from the chapter.
Q2. Assertion (A):
The zeroes of a quadratic polynomial ax² + bx + c are the x-coordinates of the points where the parabola y = ax² + bx + c intersects the x-axis.
Reason (R):
A zero of a polynomial p(x) is defined as any value k where p(k) = 0, and on the graph, this corresponds to y = 0, which is the x-axis.
Answer: A — Both A and R are true, and R is the correct explanation of A — Both the assertion and reason are true, and the reason correctly explains the assertion. When p(x) = 0, the point (x, 0) lies on both the curve and the x-axis. The zeroes are precisely the x-coordinates of intersection points with the x-axis, which is what the reason establishes.
Q3. Assertion (A):
A quadratic polynomial can have at most 3 distinct zeroes.
Reason (R):
The number of zeroes of a polynomial is determined by its degree, and a polynomial of degree n has at most n zeroes.
Answer: D — A is false but R is true — The assertion is false. A quadratic polynomial has degree 2, so it can have at most 2 zeroes, not 3. While the reason statement is generally true (a polynomial of degree n has at most n zeroes), it actually contradicts the assertion rather than supporting it. Since the assertion is false, the answer is D.
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Case Study:
A manufacturing company produces cylindrical containers where the volume V of each container is given by the polynomial function V(r) = πr² × h, where r is the radius and h is the height (both in cm). For a specific production line, the height is fixed at 10 cm. The volume function becomes V(r) = 10πr². A quality control engineer needs to find the radius values that would result in zero volume (which occurs only when radius is zero, indicating a degenerate case). The engineer is studying various radius values: r = 0, r = 2, r = 3, and r = 5 cm, and calculating corresponding volumes to understand the relationship between radius changes and volume output.
Q1. What is the degree of the polynomial function V(r) = 10πr² with respect to r?
Answer: B
Q2. What is V(0) for the volume function V(r) = 10πr²?
Answer: B
Q3. Calculate V(2) for V(r) = 10πr².
Answer: A
Q4. What is the zero of the polynomial V(r) = 10πr²?
Answer: A
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Real CBSE board exam questions from past papers — free to attempt.
CBSE 2026 · Set 31/4/1 · 1 mark
The graph of polynomial p(x) = k is shown here. Number of zeroes of polynomial p(x) is:
CBSE 2026 · Set 31/4/1 · 2 marks
If α, β are the zeroes of polynomial p(x) = 6x² – 5x – 3, then find the value of 1/α + 1/β.
CBSE 2026 · Set 31/4/2 · 2 marks
If α and β are the zeroes of polynomial p(x) = – 9x² – 6x + 1. Find the value of α² + β².
CBSE 2026 · Set 31/4/3 · 2 marks
Form a quadratic polynomial whose sum and product of the zeroes are 1/2 and –1/9 respectively. Hence, find the zeroes of the polynomial.
CBSE 2026 · Set 31/5/1 · 1 mark
The graph of a polynomial p(x) is shown here. The number of zeroes of the polynomial p(x) is
CBSE 2026 · Set 31/5/1 · 1 mark
The value of k for which sum of the zeroes of the polynomial p(x) = 3x² – kx + 6 is 2, is
CBSE 2026 · Set 31/5/1 · 3 marks
If α and β are zeroes of the polynomial p(x) = 5x² – 7x – 3, then form a quadratic polynomial whose zeroes are α² and β².
CBSE 2026 · Set 31/5/2 · 1 mark
If the zeroes of the polynomial p(x) = 2x² – 7x + 6 are α and β, then the value of 1/α + 1/β is
CBSE 2026 · Set 31/5/2 · 3 marks
(a) Find the zeroes of the polynomial p(x) = 4x² – 8x + 3 and verify the relationship between its zeroes and co-efficients. OR (b) Form a polynomial whose zeroes are 2α and 2β, where α and β are zeroes of the polynomial p(x) = x² – 3√2x + 4.
CBSE 2026 · Set 31/5/3 · 3 marks
If α, β are zeroes of the polynomial p(x) = 5x² – 7x – 3, then form a quadratic polynomial whose zeroes are α/2 and β/2.
CBSE 2026 · Set 31/1164/30 · 1 mark
At which of the following points, the quadratic polynomial p(x) = – 3x + 18x2 – 1 intersects the positive x-axis ?
CBSE 2026 · Set 31/1164/30 · 1 mark
The graph of a quadratic polynomial f(x) passes through (5,0), (0, –1) and (–2, 0). The two factors of the polynomial are
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