Problem:
Which of the following is the same as
3−6+9−12+15−18+212−4+6−8+10−12+14?
Answer Choices:
A. −1
B. −32
C. 32
D. 1
E. 314
Solution:
We have
3−6+9−12+15−18+212−4+6−8+10−12+14=3(1−2+3−4+5−6+7)2(1−2+3−4+5−6+7)=32
The problems on this page are the property of the MAA's American Mathematics Competitions