Who is asking: Student
Level: Middle

how do you factor: Xsquared + 8x + 12




You need to look for patterns. Suppose that you have factored to get

x2 + 8x + 12 = (x +a)(x +b)

and you are going to expand the right side to check your answer. When you expand the right side you get an x2 term, an x term and a constant term. The constant term is ab. Since the constant term on te left side is 12 you know that ab=12. Thus a and b are 1 and 12, 2 and 6, or 3 and 4. Expand them one at a time to see which one give 8x as the middle term.

(x + 1)(x + 12)

(x + 2)(x + 6)

(x + 3)(x + 4)



Go to Math Central