Question

Calcule o valor de x3+ 1/x3, sabendo que x+ 1/x=5

Answer 1

Vamos là.

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

x + 1/x = 5

(x + 1/x)^3 = 5^3 = 125

3*(x + 1/x) = 3*5 = 15

x^3 + 1/x^3 = 5^3 - 3*5 = 125 - 15 = 110