Question

if x-1/x=4.find x power 2 +1/x square

Answer 1

just square first eqn.. u will get
X square. +(1/x sq.) -2=16
X square. +(1/x sq) =18

Answer 2

x - 1/x = 4

squaring on both sides,
(x-1/x)² = 4²
x² + (1/x)² - 2(x)(1/x) = 16
x²+1/x² - 2 = 16
x² + 1/x² = 16+2
x² + 1/x² = 18