Question

Which shows one way to determine the factors of x3 – 9x2 + 5x – 45 by grouping?

x2(x – 9) – 5(x – 9)
x2(x + 9) – 5(x + 9)
x(x2 + 5) – 9(x2 + 5)
x(x2 – 5) – 9(x2 – 5)

Answer 1

x(x2 + 5) – 9(x2 + 5)

Explanation:

Answer 2

C

Explanation:

x(x2 + 5) – 9(x2 + 5)

= x³ + 5x - 9x² - 45

(try to expand one by one of the answer given)