Find the coefficient of x^8 in
(x^4 +x^5 + x^6)(x^3 +x^4 +x^5) (1+x+x^2+x^3+.....) Use generating function
Please, help

Question

Find the coefficient of x^8 in 
(x^4 +x^5 + x^6)(x^3 +x^4 +x^5) (1+x+x^2+x^3+.....) Use generating function
Please, help

anonymous · Answer

any idea, friend

amistre64 · Answer

youd have to teach me what a generating function is

anonymous · Answer

lol... don't tease me, please

amistre64 · Answer

im sure i can come up with a coeff, but with a different method

anonymous · Answer

ok, tell me yours

amistre64 · Answer

x^4 +x^5 + x^6
x^3 +x^4 +x^5
----------------
x^7+x^8+x^9
        x^8+x^9+x^10
                 x^9+x^10+x^11
--------------------------
x^7 + 2x^8 + other stuff that will go above x^8

amistre64 · Answer

1+x+x^2+x^3+.....
x^7+2x^8
--------------
x^7+x^8+x^9+x^10+.....
    +2x^8+2x^9+...
-------------------
       3x^8

anonymous · Answer

got it, friend

anonymous · Answer

thanks a lot. sorry, I didn't realize that you got the final answer. Lol .

anonymous · Answer

one more question. if jx^7/1-x =$$\sum_{k=0}^{\infty}\left(\begin{matrix}k+1 \ 1\end{matrix}\right)x^k+7$$

anonymous · Answer

the last one is x^(k+7)

anonymous · Answer

sorry, my bad computer. x^7 / 1-x = sum (k+1 choose 1) of x^(k+7)