Originally Posted by

**jvignacio** hey guys, just need to check if my working out and solution is correct.

Find the coefficient of $\displaystyle x^6$ in the expansion $\displaystyle (x + 3)^8$

**My solution**

So: $\displaystyle \sum_{i=0}^{8}$ $\displaystyle \binom{8}{8-i}$ $\displaystyle (x)^{8-i}$ $\displaystyle (3)^i$

now since we need to find coefficient of $\displaystyle x^6$, therefore $\displaystyle i = 6$.

so $\displaystyle \binom{8}{2}$ $\displaystyle (1)^2$ $\displaystyle (3)^6$ = $\displaystyle 28 \times 1 \times 739$ = $\displaystyle 28 \times 739$