Difference between revisions of "2002 AMC 12P Problems/Problem 20"

(See also)
(Problem)
Line 1: Line 1:
 
== Problem ==
 
== Problem ==
How many positive [[integer]]s <math>b</math> have the property that <math>\log_{b} 729</math> is a positive integer?
+
Let <math>f</math> be a real-valued function such that
 
+
<cmath>f(x) + 2f(\frac{2002}{x}) =3x</cmath>
<math> \mathrm{(A) \ 0 } \qquad \mathrm{(B) \ 1 } \qquad \mathrm{(C) \ 2 } \qquad \mathrm{(D) \ 3 } \qquad \mathrm{(E) \ 4 } </math>
+
<math>
 +
\text{(A) }1000
 +
\qquad
 +
\text{(B) }2000
 +
\qquad
 +
\text{(C) }3000
 +
\qquad
 +
\text{(D) }4000
 +
\qquad
 +
\text{(E) }6000
 +
</math>
  
 
== Solution ==
 
== Solution ==

Revision as of 23:53, 29 December 2023

Problem

Let $f$ be a real-valued function such that \[f(x) + 2f(\frac{2002}{x}) =3x\] $\text{(A) }1000 \qquad \text{(B) }2000 \qquad \text{(C) }3000 \qquad \text{(D) }4000 \qquad \text{(E) }6000$

Solution

If $\log_{b} 729 = n$, then $b^n = 729$. Since $729 = 3^6$, $b$ must be $3$ to some factor of 6. Thus, there are four (3, 9, 27, 729) possible values of $b \Longrightarrow \boxed{\mathrm{E}}$.

See also

2002 AMC 12P (ProblemsAnswer KeyResources)
Preceded by
Problem 19
Followed by
Problem 21
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 12 Problems and Solutions

The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. AMC logo.png