B) 2 –
C)
D) 28 – 14
Multiplying by One
(in Disguise)
In order to keep a fraction
the same, you must multi-
ply by 1. If you multiply the
numerator of a fraction by
the conjugate, you must do
that same operation to the
denominator or you have
changed the fraction:is the same thing as
multiplying × 1.Here’s How to Crack It
None of the answer choices have i in the denominator, if they have a denominator at all, so you need to get
rid of that i. Roots in denominators are generally not accepted, either. To get rid of both things, you need
to multiply the whole fraction by the conjugate of the denominator. This means keep the same terms, but
switch the sign between them. Be very careful to not make a sign error as you work through the problem.
The expression becomes
Multiply the two fractions, using FOIL on the denominators to get
Combine like terms in the denominator, and the expression becomes