Question

Which of the following is the correct expansion of (x + 3)(x - 4)?

A.x2 - 7x + 12


B.x2 - x + 12


C.x2 + 7x - 12


D.x2 - x - 12

Answer 1

Using FOIL (First, Outer, Inner, Last):

(x+3)(x-4)

FIRST: multiply x times x to get x^2.

OUTER: multiply x times -4 to get -4x.

INNER: multiply 3 times x to get 3x.

LAST: multiply 3 times -4 to get -12.

Your expression now looks like:

x^2-4x+3x-12

Combine like terms.

x^2-x-12

The answer is D. x^2-x-12.

I hope this helps :)