factor the following expression $25x^2 +5xy -6y^2$ How to factor
$$25x^2 +5xy -6y^2$$
I tried with $5x(5x+y)-6y^2$. I'm stuck here. 
I can't continue.  

Or just use $abc$ formula, with $a = 25$, $b = 5y$ and $c = -6y^2$, and find that terms disappear like snow before the sun:
$$ \frac{-5y ^+_- \sqrt{625y^2} }{2 \times 25}$$
So $5x = -3y$ or $5x = 2y$, etc.
