Problem:
Define the operation ⋆ by a⋆b=(a+b)b. What is (3⋆5)−(5⋆3)?
Answer Choices:
A. −16
B. −8
C. 0
D. 8
E. 16
Solution:
Since 3⋆5=(3+5)5=8⋅5=40 and 5⋆3=(5+3)3=8⋅3=24, we have
3⋆5−5⋆3=40−24=(E)16.
The problems on this page are the property of the MAA's American Mathematics Competitions