We have,
If 2x−12x=13
Then, squaring both side and we get,
(2x−12x)2=(13)2
4x2+14x2−2×2x×12x=169
4x2+14x2=169+2
4x2+14x2=171
If 2x−12x=4; find :(i) 4x2+14x2(ii)8x3−18x3