How do you factor #2x^2-9x-5#?

2 Answers
smendyka
Feb 24, 2017

Play with the multiples of #2# (2x1) and #5# (5x1) to factor as:

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

George C.
Feb 25, 2017

#2x^2-9x-5 = (2x+1)(x-5)#

Explanation:

Given:

#2x^2-9x-5#

Use an AC method:

Find a pair of factors of #AC=2*5=10# which differ by #B=9#

The pair #10, 1# works.

Use this pair to split the middle term, then factor by grouping:

#2x^2-9x-5 = 2x^2-10x+x-5#

#color(white)(2x^2-9x-5) = (2x^2-10x)+(x-5)#

#color(white)(2x^2-9x-5) = 2x(x-5)+1(x-5)#

#color(white)(2x^2-9x-5) = (2x+1)(x-5)#

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