Question

if xsquare + 1upon x square =7 find the value of x cube + 1 upon x cube

Answer 1

x²+1/x²=7

Then
(x+1/x)²=x²+1/x²+2
(x+1/x)²=7+2
(x+1/x)²=9
x+1/x=3


Then

x³+1/x³

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