How do you factor #2x^2+3x-20#?

1 Answer
Nov 9, 2015

Answer:

#(x+4)(2x-5)#

Explanation:

The left and right side of the polynomial:
#5xx (4)##=20#
#2xx(-1)##=2#

How can multiply those together and add to #3#?
#5xx-1# = #-5#
and
#2xx4# = #8#
If we add #-5+8#, we get #3#!!!

Because we need #1x*(-5)=-5x#
and
#2x*4=8x#
We put each term across from each other.
So its like cross multiplying

#(1x+4)#
#(2x-5)#

Try if you get the middle term of #3x#
#(1x*-5)+(2x*4)=3x#

Now the answer can be written as #(x+4)(2x-5)#