It is given that x−1x=6
(i)
Cube both sides of the given equation,
(x−1x)3=63
x3−1x3−3×x×1x(x−1x)=216
x3−1x3−3(6)=216
x3−1x3−18=216
x3−1x3=234
(ii)
Square both sides of the given equation,
(x−1x)2=62
x2+1x2−2×x×1x=36
x2+1x2−2=36
x2+1x2=38