Question

if x^2+1/x^2=7 then find the value of x^3+1/x^3​

Answer 1

Answer : 18

Step by step explanation :

Given :

x^2+1/x^2=7

We know that,

( a + b )^2 = a^2 + 2ab + b^2

.°. (x + 1/x)^2 = x2 + 1/x2 + 2

(x + 1/x)^2 = 7 + 2

(x + 1/x)^2 = 9

Square rooting both sides,

x + 1/x = 3

Now,

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

27 = x^3 + 1/x^3 + 9

x^3 + 1/x^3 = 27 - 9

= 18

Thus,

Value of x^3+1/x^3 is 18.

Answer 2

hope it helps...................