Question

plz tell this answer with step by step explaination​

Answer 1

Answer:

18

Step-by-step explanation:

Given Equation is x^2 + 1/x^2 = 7

∴ (x + 1/x)^2 = x^2 + 1/x^2 + 2 * x * 1/x

                    = x^2 + 1/x^2 + 2

                    = 7 + 2

                    = 9

⇒ (x + 1/x) = 3

Now,

(x^3 + 1/x^3) = (x + 1/x)^3 - 3 * x * 1/x * (x + 1/x)

                    = (x + 1/x)^3 - 3(x + 1/x)

 

                   = (3)^3 - 3(3)

                  = 27 - 9

                  = 18.

Hope it helps!