Question

x²+(1/x² )=7, find x³+1/x³​

Answer 1

Answer:

18

Step-by-step explanation:

(x + 1/x)² = x² + 1/x² + 2

→ (x + 1/x)² = 7 + 2

→ (x + 1/x)² = 9

→ x + 1/x = 3

→ x³ + 1/x³ = (x + 1/x)(x² + 1/x² - 1)

→ x³ + 1/x³ = (3)(7- 1)

→ x³ + 1/x³ = (3)(6)

→ x³ + 1/x³ = 18