Question

if x-y=5 and xy=7, find the value of x^3-y^3.

Answer 1

Step-by-step explanation:

Using Identities,

a³ - b³ = (a-b)(a² + b² + ab)

a² + b² - 2ab = (a-b)²

x³ - y³ = (x - y)(x² + y² + xy)

= 5 × ( x² + y² - 2xy + 3xy)

= 5 × ( (x-y)² + 3xy)

= 5 ×(5² + 3×7)

= 5× (25 + 21)

= 430