Question

If x=(5-3)/21 find the value of (x^3+1/x3)-5(x^2+1/x^2)+(x+1/x)

Answer 1

Assuming the question as (x + 1/x) = 3. Squaring on both the sides we get (x + 1/x)2 = 32 x2 +(1/x2) + 2 = 9 ⇒ x2 +(1/x2) = 7. Now cubing ...