SOLUTION: Factor the quadratic equation. {{{ 5x^2-19x-4 }}} Like my last question, I don't understand how one can get the factors of -4 and then find the sum of -19 with those factors.

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: Factor the quadratic equation. {{{ 5x^2-19x-4 }}} Like my last question, I don't understand how one can get the factors of -4 and then find the sum of -19 with those factors.      Log On


   



Question 173399: Factor the quadratic equation.
+5x%5E2-19x-4+
Like my last question, I don't understand how one can get the factors of -4 and then find the sum of -19 with those factors.

Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
5x%5E2-19x-4 you must start with the factors that you know
:
in the first terms of the factoring you have a combo of 5x and x as choices. In the second terms you have 1 and 4 as the possibles......so we need to maneuver those to meet our goal the middle term of -19x which always comes from a combination of the o and i(the outside and inside terms) in foil(first,outside,inside,last)
:
%285x%2B1%29%28x-4%29...... the 5x has to be combined with the 4 while the x is combined with the one.....so as to get that -19x ( the outside(o) term is 5x(-4) and the inside(i) term is 1(x))... you must remember when you have a coefficient larger than 1 in the squared term it makes it more of a guessing game...This one is rather simple because there arent that many choices......Ther first terms are usually pretty easy....but sometimes the second terms can have multiple combinations to test.
:
system%28x=4%2Cx=-1%2F5%29