Carcass wrote:
What must be added to \(\frac{x + y}{2}\) to obtain \(\frac{x - y}{2}\)?
A. –y
B. –x
C. 2y
D. 2x
E. y – x
TIP: If the wording of a question is confusing, and you're not sure what mathematical operation is required, ask yourself an easier question. For example, for this question, we might ask
"What must be added to 2 to obtain 5?" The answer to this easier question = 5 - 2
This means the answer to the original question \(= \frac{x - y}{2} - \frac{x + y}{2}\)
\(= \frac{(x - y) - (x + y) }{2}\)
\(= \frac{-2y}{2}\)
\(= -y\)
Answer: A