Expert: Scott A Wilson - 5/25/2010

Question
3. Simplify (2x + 3)(x − 4) = ?
A. 2x 2 + 5x − 12   C. 2x2 − 5x + 12
B. 2x2 − 5x − 12     D. 2x2 + 5x + 12

I say my answer is d

Answer
To do it right, split apart the problem into 2x(x-4) and 3(x-4).
Given that, we can then split 2x(x-4) + 3(x-4) into four parts.
2x*x gives the 2x², which all the answeres have.

The next number in the 1st term is 2x(-4) = -8x.
The 1st number in the 2nd term is 3(x) = 3x.
When this is added to -8x, -5x is gotten.  That is in B and C.

The 2nd number in the 2nd term (or the last one to look at) is 3(-4).  That is -12.
Using this, it can be seen whether B or C is correct.