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JEE Mains · Maths · STD 12 - 1. relation and function
If \(f(x)\) is a quadratic expression such that \(f(1) + f (2)\, = 0\) , and \(-1\) is a root of \(f(x)\, = 0\), then the other root of \(f(x)\, = 0\) is
- A \( - \frac{5}{8}\)
- B \( - \frac{8}{5}\)
- C \( \frac{5}{8}\)
- D \( \frac{8}{5}\)
Answer & Solution
Correct Answer
(D) \( \frac{8}{5}\)
Step-by-step Solution
Detailed explanation
If \(a\) and \(-1\) are the roots of the polynomial, then we get \(f\left( x \right) = {x^2} + \left( {1 - a} \right)x - a\) \(\therefore f\left( 1 \right) = 2 - 2a\) and \(f\left( 2 \right) = 6 - 3a\) As, \(f\left( 1 \right) + f\left( 2 \right) = 0\)…
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