Question

What are the factors of x2 + 3x - 4?

(x + 4) and (x - 4)
(x + 3) and (x-4)
(x + 4) and (x - 1)
(x + 3) and (x - 1)

Answer 1

C. (x + 4) and (x - 1)

Explanation:

The middle number is 3 and the last number is -4.

Factoring means we want something like

(x+_)(x+_)

Which numbers go in the blanks?

We need two numbers that...

Add together to get 3

Multiply together to get -4

Can you think of the two numbers?

Try -1 and 4:

-1+4 = 3

-1*4 = -4

Fill in the blanks in

(x+_)(x+_)

with -1 and 4 to get...

(x + 4) and (x - 1)