Question

What is the factored form of x2 - 12x - 45?

Answer 1

Answer:

(x - 15)(x + 3)

Step-by-step explanation:

Factors of 45 include 5 and 9, 3 and 15, 1 and 45, and so on.

Note that 3*15 =+45; this is not what we wanted.  Thus, try (-3)*15 = -45.

Do -3 and 15 combine to yield -12?  No.  Thus drop (-3)(15) and try (3)(-15).

Do 3 and -15 combine to yield -12?  YES

Therefore, the factored form of x² - 12x - 45 is (x - 15)(x + 3).