Find the coefficient of $\displaystyle x^7$ in the expansion of $\displaystyle (2x^2+\frac{1}{x})^{11}$

I found $\displaystyle r=7\frac{1}{3}$ and could not work with a fraction....

Basically, I equated the powers of x to zero,

$\displaystyle 2(11-r)-r=0$

and found $\displaystyle r=7\frac{1}{3}$