How do you factor #y= 2x^2 - 9x – 18# ?

1 Answer
Roella W.
Dec 30, 2015

#y = (2x +3)(x - 6)#

Explanation:

If the factored quadratic is expressed as #(ax +b)(cx+d)# then the general form of a quadratic is #y = acx^2 +(bc + ad)x +bd#
We therefore need to look for factors of #2# and #(-18)# that will combine to give #(-9)#
Possible factors of #2# are only #2# and #1#
Possible factors of #(-18)# are #-9# and #2# or #-6# and #3#
#2*(-6) +1*3 = -9# so these are the correct factors.
Hence #y = (2x +3)(x - 6)#

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