Expand the following identity.
(2x+1)3
8x3+1+12x2+6x
We know that (x+y)3 = x3+y3+3xy(x+y)
= x3+y3+3x2y+3xy2 -----(i)
Comparing the question with the identity, we have x = 2x, y = 1
Substitute the value of x and y in (i), we get:
(2x+1)3 = (2x)3+13+3(2x)2(1)+3(2x)(1)2
= 8x3+1+12x2+6x.