How do you factor the expression #x^2 +7x-8#?

1 Answer
May 12, 2016

Answer:

#x^2+7x-8 = (x-1)(x+8)#

Explanation:

Given #x^2+7x-8#

Note that the sum of the coefficients is #0#. That is #1+7-8 = 0#.

So #x=1# is a zero and #(x-1)# a factor:

#x^2+7x-8 = (x-1)(x+8)#

The linear factor #(x+8)# can be constructed by looking at the coefficients of #x^2# and the constant term #-8# that we want in the product:

  • Since the coefficient of #x^2# is #1# in the product, we require a coefficient #1# for #x#.

  • Since the constant term is #-8# in the product, we require a constant #+8# in the factor which will become #-8# when multiplied by #-1#.