# Math Help - power series expansion

1. ## power series expansion

what is the coefficient of x^2 in the power series expansion of (4 + 7x)^(1/3)?

2. Try a Taylor expansion:

$f(x)=f(a)+(x-a)\frac{\partial}{\partial x} f(a) + \frac{(x-a)^{2}}{2!} \frac{\partial^{2}}{\partial x^{2}} f(a) + ...$

Use $a = 0$, and take the necessary derivatives. The third term in the above series is what you're looking for.