Question

If x+1/x=4,find the value of (x-1/x)^2

Answer 1

`\left(x-(1)/(x)\right)^2=\\ x^2-2+(1)/(x^2)=\\ x^2+2+(1)/(x^2)-4=\\ \left(x+(1)/(x)\right)^2-4=\\ 4^2-4=16-4=12`