Question

39. Find the value of a3 + b3 - 15ab + 125, when a +b=-5​

Answer 1

Answer:

It becomes a^3 + b^3 + 15ab - 125 = 0 . This means a + b = 5 . A and B must be real , so the solution is A = 0 and B = 0 only . This means a = -5 and b = -5 , a + b = -10