Question

Factored form x^2 - 4x - 21?

Answer 1

ANSWERS:

2

−

4

−

2

1

x^{2}-4x-21

x2−4x−21

Grouping

1

Use the sum-product pattern

2

−

4

−

2

1

x^{2}{\color{#c92786}{-4x}}-21

x2−4x−21

2

+

3

−

7

−

2

1

x^{2}+{\color{#c92786}{3x}}{\color{#c92786}{-7x}}-21

x2+3x−7x−21

2

Common factor from the two pairs

3

Rewrite in factored form

Solution

(

−

7

)

(

+

3

)