Question

if x + 1/x = 5, find the value of x^3 + 1/x^3

Answer 1

Answer:

x=5/3 your answer right answer

Answer 2

Answer:

110

Step-by-step explanation:

The expansion (a + b)³ is

(a + b)³ = a³ + b³ + 3ab(a + b)

Then

(x + $\frac{1}{x}$ )³ with a = x and b = $\frac{1}{x}$

= x³ + $\frac{1}{x^3}$ + 3x . $\frac{1}{x}$ (x + $\frac{1}{x}$ )

Thus

x³ + $\frac{1}{x^3}$ = (x + $\frac{1}{x}$ )³ - 3(x + $\frac{1}{x}$ )

           = 5³ - 3(5)

           = 125 - 15

           = 110