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TS EAMCET · Maths · Quadratic Equation

If the expression \(7+6 x-3 x^2\) attains its extreme value \(\beta\) at \(x=\alpha\), then the sum of the squares of the roots of the equation \(x^2+\alpha x-\beta=0\) is

  1. A 21
  2. B -19
  3. C 19
  4. D -21
Verified Solution

Answer & Solution

Correct Answer

(A) 21

Step-by-step Solution

Detailed explanation

Given expression is \(7+6 x-3 x^2=f(x)\)...(i) Extreme value of \(f(x)\) is \(\beta=\frac{-D}{4 a}\) which occurs at \(\alpha=\frac{-b}{2 a}\) \(a=-3, b=6, c=7\) (on comparing (i) with \(a x^2+b x+c\) ) \(\beta=\frac{-(36+84)}{(4 \times-3)}=10 ; \alpha=\frac{-6}{-6}=1\)…