Question

If x + 1/x =20, find the value of x2 + 1/ x2

Answer 1

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Answer 2

Answer:

Step-by-step explanation:

$x+\dfrac{1}{x}=20\\\\Squar \ both \ side\\\\(x+\dfrac{1}{x})^{2}=20^{2}\\\\x^{2}+\dfrac{1}{x^{2}}+2*x*\dfrac{1}{x}=400\\\\x^{2}+\dfrac{1}{x^{2}}+2=400\\\\x^{2}+\dfrac{1}{x^{2}}=400-2\\\\x^{2}+\dfrac{1}{x^{2}}=398$