Don’t forget tricks such as the difference of squares, which makes factoring the denominator very
easy. The key now is to notice that h − 4 and 4 − h are opposites of each other, so you can factor out
−1 in the numerator and cancel them out:
This is equivalent to answer choice (C):
If you get stuck while factoring, it helps to realize that the top and bottom must have a factor in
common—otherwise the test makers wouldn’t be asking the question. If you can factor either one
completely, it will provide a good start on the other expression.
Alternative method: Here’s another way to answer this question. Pick a number for h and see what
happens. One of the answer choices will give you the same value as the original fraction will, no
matter what you plug in for h. Pick a number that’s easy to work with—like 0.
PICK NUMBERS.
When the answer choices are algebraic expressions, it often works to pick numbers for the
unknowns, plug those numbers into the stem and see what you get, and then plug those
same numbers into the answer choices to find matches.Warning: When you pick numbers, you have to check all the answer choices. Sometimes
more than one works with the number(s) you pick, in which case you have to pick numbers
again.