To factor polynomials of the form
x2 +
bx +
c, begin with two pairs of parentheses with
x at the left of each.
Next, find two integers whose product is
c and whose sum is
b and place them at the right of the parentheses.
Example 1: Factor
x2 + 8
x +12.
12 can be factored in a variety of ways:
The only combination whose sum is also 8 is (2)(6), so
Example 2: Factor
x2 − 7
x − 18.
−18 can be factored in the following ways:
The only combination whose sum is also −7 is (2)(−9), so
Example 3: Factor
x2 − 6
x +9.
9 can be factored as
The only combination whose sum is −6 is (−3)(−3), so