Question

If x sq + 1/x sq =51 find the value of x cube -1/x cube

Answer 1

Answer:

364

Step-by-step explanation:

x² + 1/x² = 51

x² + (1/x)² - 2 (x) (1/x) = 51 - 2

(x - 1/x)² = 49  (a² + b² + 2ab = (a+b)² )

x - 1/x =√49 = 7

(x - 1/x)³ = x³ - (1/x)³ - 3(x)(1/x)(x - 1/x)

7³ = x³ - 1/x³ - 3 × 7

343 = x³ - 1/x³ - 21

x³ - 1/x³ = 343 + 21

x³ - 1/x³ = 364