How do you factor #15x^2 + 8x - 12#?

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Answer 1 · 2015-05-22T07:06:19

We can Split the Middle Term of this expression to factorise it

In this technique, if we have to factorise an expression like #ax^2 + bx + c#, we need to think of 2 numbers such that:

#N_1*N_2 = a*c = 15*-12 = -180#
and,
#N_1 +N_2 = b = 8#

After trying out a few numbers we get:
#N_1 = -10# and #N_2 =18#

#-10*18 = -180#, and #(-10)+ 18= 8#

#15x^2+8x-12 = 15x^2 -10x + 18x -12#

#= 5x(3x - 2) + 6(3x -2)#

# = (5x +6)(3x-2)# , this is the factorised form.