(x-4)(x-3)
FOIL to check
x² -3x -4x +12
x² -7x +12
The answer should be D after you simplify it all.
The answer to the question
Answer:

Step-by-step explanation:
So we know already that, in order to find the area of a triangle, we need to find base * height / 2. That doesn't change when we have variables involved, it just gets a little more complicated.
The trick is we need to just dumb down and not overthink anything. Just foil like normal.
FOIL = First Outer Inner Last, it's a way of multiplying. Basically, you take multiply the first variables, the second variables, the inner variables, and then the last variables.

Now you <em>could</em> just keep it in that form, but I personally would rather simplify it into decimals to get 
Additionally, if your answer choices do not include decimals, try either 8x^2 - 9/2 , or (16x^2 - 9)/2