maths
posted by George on .
find the first 3 terms in the expansion of (x+4)(1+3x)^2 as a series in ascending powers.
I expanded the second bracket using binomial expansion and got 1 6x +27x^2 108x^3
how do I combine (x+4) with the expansion?
Any help would be appreciated.

just multiply out as usual, taking only the firet 3 terms:
(1 6x +27x^2 108x^3)(4+x)
= (1 6x +27x^2 108x^3)*4
+ (1 6x +27x^2 108x^3)*x
= 4  24x + 108x^2  ...
+ x  6x^2 + 27x^3  ...

4  23x + 102x^2 + ...