The sum of squares of roots of the equation $x^{\frac{2}{3}}+x^{\frac{1}{3}}-2=0$ is

The sum of squares of roots of the equation $x^{\frac{2}{3}}+x^{\frac{1}{3}}-2=0$ is
  1. 82
  2. 65
  3. 50
  4. 37

Solution

Given, equation is $ \begin{array}{rlrl} & & x^{2 / 3}+x^{1 / 3}-2 & =0 \\ \Rightarrow & & x^{2 / 3}+x^{1 / 3} & =2 \\ & \Rightarrow & \left(x^{2 / 3}+x^{1 / 3}\right)^3 & =2^3 \\ & & & \\ {\left[\therefore(a+b)^3\right.} & \left.=a^3+b^3+3 a b(a+b)\right] \end{array} $ $\begin{aligned} & \Rightarrow \quad x^2+x+3 x \times 2=8 \Rightarrow \\ & x^2+7 x-8=0 \\ & \Rightarrow \quad(x+8)(x-1)=0 \Rightarrow x=1 ;-8 \\ & \text { Sum of square roots }=(1)^2+(-8)^2 \\ & \quad=1+64=65\end{aligned}$

Asked in: AP EAMCET 2022 (06 Jul Shift 2)

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