Problem:
For the nonzero numbers a,b, and c, define
(a,b,c)=ba+cb+ac
Find (2,12,9).
Answer Choices:
A. 4
B. 5
C. 6
D. 7
E. 8
Solution:
We have
(2,12,9)=122+912+29=61+34+29=61+8+27=636=6.
Answer: C.
The problems on this page are the property of the MAA's American Mathematics Competitions