Question

if x^2+1/x^2=79 find the value of x^3+1/x^3

Answer 1

(x+1/x)²=x²+1/x²+2
(x+1/x)²=79+2
(x+1/x)²=81
x+1/x=9



(x+1/x)³=x³+1/x³+3(x+1/x)
(9)³=x³+1/x³+3(9)
729-27=x³+1/x³
702=x³+1/x³