NCERT Exemplar Solutions
Class 10 - Mathematics - CHAPTER 2: Polynomials - Exercise 2.1
Question 3

Question.  3

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)

\(a = 0,\; b = -6\)

Detailed Answer with Explanation:

Step 1: Recall the relationships of zeroes with coefficients.

If \(\alpha\) and \(\beta\) are the zeroes of \(x^2 + px + q\), then

\(\alpha + \beta = -p\)

\(\alpha \cdot \beta = q\)

Step 2: Apply to our polynomial.

Here, polynomial is \(x^2 + (a+1)x + b\).

So, coefficient of \(x\) is \(a+1\) and constant term is \(b\).

Thus,

Sum of zeroes \(= - (a+1)\)

Product of zeroes \(= b\)

Step 3: Use the given zeroes.

The zeroes are \(2\) and \(-3\).

So,

\(\alpha + \beta = 2 + (-3) = -1\)

\(\alpha \cdot \beta = 2 \times (-3) = -6\)

Step 4: Form equations for \(a\) and \(b\).

From sum: \(- (a+1) = -1\)

\(a+1 = 1\)

\(a = 0\)

From product: \(b = -6\)

Step 5: Final answer.

So the correct values are \(a = 0\) and \(b = -6\).

This corresponds to option D.

NCERT Exemplar Solutions Class 10 – Mathematics – CHAPTER 2: Polynomials – Exercise 2.1 | Detailed Answers