Q151 / 270 · NDA 2012 (Phase 1) · Mathematics

What is the sum of the squares of the roots of the equation $x^2+2 x-143=0$ ?

  • A
    170
  • B
    180
  • C
    190
  • Correct answer
    D
    290

Solution

If roots $\alpha, \beta$ then $\begin{aligned} \alpha+\beta & =-2 \\ \alpha \beta & =-143 \\ \alpha^2+\beta^2 & =(\alpha+\beta)^2-2 \alpha \beta \\ & =(-2)^2-2(-143) \\ & =4+286=290 . \end{aligned}$

Hence, the correct answer is option: 'D'.

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