How do you factor quadratics by grouping

Here's an example Its also call the 'ac' method:-

factor  2x^2 - 13x - 15

Multiply first coefficient by last number  which is 2*-15 = -30

Now we need 2 factors of -30 which will when added give - 13:-

-15 and 2  looks good. So we  can write:-

2x^2 - 13 x - 15

= 2x^2 + 2x - 15x - 15 

factor by grouping first 2 and last 2 terms , we get:-

= 2x(x + 1) - 15(x + 1)   

the x+1 is common so we have:-

(2x - 15)(x + 1)   Answer

Hope this helps.