2009 AMC 12A Problems/Problem 9
Contents
[hide]Problem
Suppose that and . What is ?
Solution
Solution 1
As , we have .
To compute , set in the first formula. We get .
Solution 2
Combining the two formulas, we know that .
We can rearrange the right hand side to .
Comparing coefficients we have , , and . From the second equation we get , and then from the third we get . Hence .
See Also
2009 AMC 12A (Problems • Answer Key • Resources) | |
Preceded by Problem 8 |
Followed by Problem 10 |
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All AMC 12 Problems and Solutions |