Question

If: x-1/x=√5. Find: 2(x²+1/x²)​

Answer 1

Answer:

14

Step-by-step explanation:

x - 1/x = √5

We know that :

( x - 1/x )^2 = x^2 + 1/x^2 -2

or x^2 + 1/x^2 = ( x - 1/x )^2 +2

or x^2 + 1/x^2 = (√5)^2 +2

or x^2 + 1/x^2 = 7

Than 2(x^2 + 1/x^2) = 14