How do you factor #4x^2+2x-20#?

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Answer 1 · 2015-08-11T16:46:53

#color(blue)((2x-4)(2x+5) # is the factorised form of the expression.

#4x^2+2x−20#

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 = 4*-20 = -80#
and
#N_1 +N_2 = b = 2#

After trying out a few numbers we get #N_1 = 10# and #N_2 =-8#
#10*(-8) = -80#, and #10+(-8)= 2#

#4x^2+color(blue)(2x)−20 =4x^2+color(blue)(10x -8x)−20#

# =2x(2x+5) -4(2x+5)#
#color(blue)((2x-4)(2x+5) # is the factorised form for the expression.