Question

Which is the completely factored form of 12x3 – 60x2 + 4x – 20? 4(3x2 – 1)(x – 5) 4x(3x2 + 1)(x – 5) 4x(3x2 – 1)(x + 5) 4(3x2 + 1)(x – 5)

Answer 1

The answer is 4(3x² + 1)(x - 5).

Explanation:

First, you have to take out all the common ratios :

12x³ - 60x² + 4x - 20

= 4(3x³ - 15x² + x - 5)

Next, you have to factorize the inner brackets :

3x³ - 15x² + x - 5

= 3x²(x - 5) + (x - 5)

= (3x² + 1)(x - 5)

Answer 2

4(3x² + 1)(x - 5)

Explanation:

Given

12x³ - 60x² + 4x - 20 ← factor out 4 from each term

= 4(3x³ - 15x² + x - 5)

Factor the first/second and third/fourth terms inside the parenthesis

= 4[ 3x²(x - 5) + 1(x - 5) ] ← factor out (x - 5) from each term

= 4(3x² + 1)(x - 5)