Question

If (x -1/x)=5,the value of x sq +1/x sq is ?

Answer 1

given (x-1/x)=5
(x-1/x)²=5²
(x-1/x)²=25
x²+1/x²-2×x×1/x=25
x²+1/x²-2=25
x²+1/x²=25+2
x²+1/x²=27

Answer 2

use the formula a² + b² = [(a - b)² + 2ab].

x² + (1/x²) = [(x - 1/x)² + 2(x)(1/x)] = [(x- 1/x)² + 2] = (5² +2) = 25+2 = 27