Bizzare diffeq calculation problems

I'm learning very basic diffeqs in another math class, and the type of problems were doing are first order separable differential equations, very basic stuff.

I'm trying to use Mathematica/Wolfram Alpha to check my answers, but everytime, wolfram will output the incorrect answer and I will always have the correct answer and I can't figure out why

For example:

$\displaystyle 7\sqrt{xy}\frac{dy}{dx}=4$

I calculated y to be:

$\displaystyle y=(\frac{3}{14}8\sqrt{x}+C)^\frac{2}{3}$

When simplified, this matches the back of my book. Great. When I type the same problem for Wolfram Alpha to solve, I get back this:

Input:

Solve $\displaystyle \frac{dy}{dx}=\frac{4}{7\sqrt{xy}}$

Output:

$\displaystyle y = \frac{3}{14}^\frac{2}{3} (8 \sqrt{x} + 7*C)^\frac{2}{3}$

Which is completely wrong. Could this be a bug in the CAS?