Finding dy/dx for $\displaystyle y^2 = 5x^3$. Find equation of the tangent line to the graph at the given point. (1, sqrt 5)

Here's what I did;

$\displaystyle 2yy' = 15x^2$

$\displaystyle y' = 15x^2 / 2y$

Where did I go wrong? Or, if it's right by some chance, how do I proceed to find the equation?