Difference between revisions of "2007 AMC 12B Problems/Problem 9"
(New page: 3x-1 =5 x= 2 4+2+1=7) |
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| − | 3x-1 =5 | + | A function <math>f</math> has the property that <math>f(3x-1)=x^2+x+1</math> for all real numbers <math>x</math>. What is <math>f(5)</math>? |
| − | x= 2 | + | |
| − | + | <math>(A)7</math> <math>(B)13</math> <math>(C)31</math> <math>(D)111</math> <math>(E)211</math> | |
| + | |||
| + | == Solution == | ||
| + | |||
| + | <math>3x-1 =5 \implies x= 2</math> | ||
| + | <math>f(3(2)-1) = 2^2+2+1=7 \implies (A)</math> | ||
Revision as of 21:46, 2 July 2008
A function 
has the property that 
for all real numbers 
. What is 
?
Solution
