Question

$(5a + 3b)^3 - (5a - 3b)^3$

Answer 1

Here we can use identity a³ - b³ = (a-b)³ + 3ab(a-b)

a = 5a + 3b b = 5a - 3b

∴ (5a + 3b)³ - (5a - 3b)³ = (5a + 3b - 5a + 3b)³ + 3(5a + 3b)(5a + 3b - 5a + 3b) = (6b)³ + 18b(15a + 9b) = 216b³ + 270a + 162b

Hope this helps :)

Answer 2

hi mate,

solution: (5a+3b)³-(5a-3b)³

= (5a)³+3*(5a)²*3b+3*5a*(3b)²+(3b)³- [(5a)³-3*(5a)²*3b+3*5a*(3b)²-(3b)³]

=(5a)³+3*(5a)²*3b+3*5a*(3b)²+(3b)³-(5a)³+3*(5a)²*3b-3*5a*(3b)²+(3b)³

=2*3*(5a)²*3b+2*(3b)³

=450a²b+54b³

i hope it helps you.