NCERT Exemplar Solutions
Class 10 - Mathematics - CHAPTER 2: Polynomials - Exercise 2.3
Question 10

Question. 10

Find the zeroes of \(7y^2-\dfrac{11}{3}y-23\) and verify relations.

Answer:

\(y=\dfrac{11+\sqrt{5917}}{42},\; y=\dfrac{11-\sqrt{5917}}{42}\)

Detailed Answer with Explanation:

Step 1: Identify coefficients.

\(a = 7,\; b = -\dfrac{11}{3},\; c = -23\)

Step 2: Discriminant.

\(b^2 - 4ac = \left(-\dfrac{11}{3}\right)^2 - 4(7)(-23)\)

= \(\dfrac{121}{9} + 644\)

= \(\dfrac{5917}{9}\)

So, \(\sqrt{\Delta} = \dfrac{\sqrt{5917}}{3}\)

Step 3: Roots.

\(y = \dfrac{ -b \pm \sqrt{\Delta} }{ 2a }\)

= \(\dfrac{ \dfrac{11}{3} \pm \dfrac{\sqrt{5917}}{3} }{ 14 }\)

= \(\dfrac{ 11 \pm \sqrt{5917} }{ 42 }\)

Step 4: Verify.

Sum = \(\dfrac{11 + \sqrt{5917}}{42} + \dfrac{11 - \sqrt{5917}}{42}\)

= \(\dfrac{22}{42} = \dfrac{11}{21}\)

= \(-\dfrac{b}{a} = -\dfrac{-11/3}{7} = \dfrac{11}{21}\)

Product = \(\dfrac{(11 + \sqrt{5917})(11 - \sqrt{5917})}{42^2}\)

= \(\dfrac{121 - 5917}{1764}\)

= \(\dfrac{-5796}{1764}\)

= \(-\dfrac{23}{7}\)

= \(\dfrac{c}{a}\)

NCERT Exemplar Solutions Class 10 – Mathematics – CHAPTER 2: Polynomials – Exercise 2.3 | Detailed Answers