Question

se x+1/x=84, calcule x^2+1/x^2

Answer 1

$x+\frac{1}{x}=84\\\\(x+\frac{1}{x})^2=(84)^2\\\\x^2+2\cdot\,x\cdot\frac{1}{x}+\frac{1}{x^2}=7056\\\\x^2+2+\frac{1}{x^2}=7056\\\\\boxed{x^2+\frac{1}{x^2}=7054}$