Solve this following

Question:

Let $\alpha, \beta$ be two roots of the equation

$x^{2}+(20)^{1 / 4} x+(5)^{1 / 2}=0 .$ Then $\alpha^{8}+\beta^{8}$ is equal to

 

  1. 10

  2. 100

  3. 50

  4. 160


Correct Option: , 3

Solution:

$\left(x^{2}+\sqrt{5}\right)^{2}=\sqrt{20} x^{2}$

$x^{4}=-5 \Rightarrow x^{8}=25$

$\alpha^{8}+\beta^{8}=50$

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