Difference between revisions of "1991 AIME Problems/Problem 7"
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Revision as of 19:22, 4 July 2013
Problem
Find , where is the sum of the absolute values of all roots of the following equation:
Solution
Let . Then , from which we realize that . This is because if we expand the entire expression, we will get a quadratic. As this quadratic will have two roots, they must be the same roots as the quadratic .
The given finite expansion can then be easily seen to reduce to the quadratic equation . The solutions are . Therefore, . We conclude that .
See also
1991 AIME (Problems • Answer Key • Resources) | ||
Preceded by Problem 6 |
Followed by Problem 8 | |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 | ||
All AIME Problems and Solutions |
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions.