Binomal expansion?

Question

find the coefficient of x^3 in the boinomal expansion of (1+2x)^8

i got the answer as 56?

Answer 1

c(8,r) 1^(8-r) (2x)^r

8C(8,3)=8*6*7*8/6
Answer: 8*56=448

Answer 2

yep u are right^^
should be equal to 8C3 which is 56
if u expend it:
1^8 + 8(1)x + 28(1)(x)^2 +56(1)(x)^3+...