Question 962634
2x^2 - 7x - 4 = 0
multiply 2 * 4 to get 8
look for the factors of 8 that add up to or subtract from each other to get -7
since the coefficient of the x term is negative and the coefficient of the constant term is also negative, you will be looking for factors that subtract from each other to get 7.


8 * 1 = 8 and 8 - 1 = 7
they look like they'll do.


split the middle term into -8x and +x to get:
2x^2 - 8x + x - 4 = 0
associate the first two terms together and the last two terms together to get:
(2x^2 - 8x + (x - 4) = 0
factor the first associated terms so that (x - 4) is one of the factors.
you will get:
2x * (x-4) + (x-4) = 0
this is equivalent to:
2x * (x-4) + 1 * (x-4) = 0
factor out the common term of (x-4) to get:
(2x + 1) * (x-4) = 0
those are your factors.

read this tutorial on factoring.
it should help.
<a href = "http://www.purplemath.com/modules/factquad.htm" target = "_blank">http://www.purplemath.com/modules/factquad.htm</a>