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.
Forget about the $y$ for a second. 

If you want to factor $25x^2 + 5x - 6$, look for two numbers whose product is $25 \cdot -6 = -150$ and whose sum is $5$. It takes just a moment to see that the two numbers are $15$ and $-10$. Then:
\begin{align*}
25 x^2 + 5x - 6 &amp;= 25 x^2 + (15x - 10x) - 6 \\ &amp;= (25 x^2 + 15x) - (10x + 6) \\ &amp;= 5x(5x + 3) - 2(5x + 3) \\&amp; = (5x-2)(5x+3).\end{align*}

With the $y$ included the process is nearly identical:
\begin{align*}
25 x^2 + 5xy - 6 y^2&amp;= 25 x^2 + (15xy - 10xy) - 6y^2 \\ &amp;= (25 x^2 + 15xy) - (10xy + 6y^2) \\ &amp;= 5x(5x + 3y) - 2y(5x + 3y) \\&amp; = (5x-2y)(5x+3y).\end{align*}
The answer is $(5x-2y)(5x+3y)$.