How do you factor #x^2-8x-20#?

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Answer 1 · 2016-04-10T16:57:54

# ( x + 2 ) ( x - 10 ) # is the factorised form of the expression.

#x^2 - 8x - 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 = 1*-20 =- 20 #

AND

#N_1 +N_2 = b = -8#

After trying out a few numbers we get #N_1 = 2 # and #N_2 =-10#
#2 * (-10) = -20#, and #2+(-10)= - 8#

#x^2 - 8x - 20 = x^2 - 10x + 2x - 20 #

#=x ( x - 10 ) + 2 ( x - 1 0)#

# ( x + 2 ) ( x - 10 ) # is the factorised form of the expression.