Question

expand : 1. (2a+3b)^3

2. (4a-5b)^3

Answer 1

Hola there,

Formula => (a + b)³ = a³ + b³ + 3ab(a + b)
(a - b)³ = a³ - b³ - 3ab(a - b)

So,

1) (2a + 3b)³ = (2a)³ + (3b)³ + 3(2a)(3b)(2a + 3b)

= 8a³ + 27b³ + 18ab(2a + 3b)

= 8a³ + 27b³ + 36a²b + 54ab²

2) (4a - 5b)³ = (4a)³ - (5b)³ - 3(4a)(5b)(4a - 5b)

= 64a³ - 125b³ - 60ab(4a - 5b)

= 64a³ - 125b³ - 240a²b + 300ab²

Hope this helps...:)