Question

Identify the factors of x^2 - 4x – 21.

1. (x - 7)(x + 3)

2. (x + 7)(x - 3)

3. (x + 21)(x - 1)

4. (x - 21)(x + 1)

Answer 1

1

Explanation:

X²-4x-21

-21×x²=-21x²

the factors of -4x and -21x² are -7x and 3x

x²-7x+3x-21

(x²-7x)+(3x-21)

X(x-7)+3(x-7)

answer:(x-7)(X+3)

Answer 2

1. (x - 7)(x + 3)

Explanation:

x^2 - 4x – 21

We need two numbers that have a product of -21 and a sum of -4.

The numbers are -7 and 3 since -7 * 3 = -21, and -7 + 3 = -4

x^2 - 4x – 21 = (x - 7)(x + 3)

Answer: (x - 7)(x + 3)