Question

find the value of a³+b³ if a+2b=10 and ab=15​

Answer 1

Answer:

Given a +2b = 10 and ab = 15

Consider, a3 + 8b3 = a3 + (2b)3

= (a + 2b)3 − 3 × a × 2b(a + 2b)

[Since, a3 + b3 = (a + b)− 3ab(a + b)] = (a + 2b)3 − 6ab(a + 2b)

= (10)3 − 6 × 15 × 10

= 1000 − 900 = 100