Question

How to factor x^3 - 4x^2 - 9x + 36 by grouping

Answer 1

Answer:

(x-4) (x-3) (x+3)

Step-by-step explanation:

x^3 - 4x^2 - 9x + 36

Make 2 groups

x^3 - 4x^2            - 9x + 36

We can factor out x^2 from the first group and -9 from the second group

x^2 (x-4)    - 9(x-4)

Now factor out (x-4)

(x-4) (x^2 -9)

This may be an answer choice but we can still factor

(x^2 -9) is the difference of squares

(x^2-9) = (x-3) (x+3)

Replacing this

(x-4) (x-3) (x+3)

Answer 2

Answer:

(x - 4)(x - 3)(x + 3)

Step-by-step explanation:

x³ - 4x² - 9x + 36

x²(x - 4) - 9(x - 4)

(x - 4)(x² - 9)

(x - 4)(x² - 3²)

(x - 4)(x - 3)(x + 3)