Question

evaluate a3-b3 when a-b =2 and a2 +b2 = 4

Answer 1

id of a^3 - b^3 = (a+b)(a2 -ab +b2)

(a-b)^2 = a^2 + b^2 -2ab

4 = 4 - 2ab

4-4 = -2ab

0 = -2ab

ab = 0

then the value of

a^3 - b^3 = (a-b)(a2 +ab +b2)

a^3 - b^3 = 2 (4 +0)

a^3 - b^3 = 8