Difference between revisions of "2002 AMC 10P Problems/Problem 12"

(Problem 12)
(Solution 1)
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== Solution 1==
 
== Solution 1==
 +
We can solve this problem with a case by case check of <math>\text{I., II., III.,}</math> and <math>\text{IV.}</math> Since <math>f_n=x^n,</math> <math>f_{2002}(a)=a^{2002}, all cases must equal </math>a^{2002}.<math>
  
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</math>\text{I. } (f_{11}(a)f_{13}(a))^{14}<math>
  
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</math>\begin{align*}
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(f_{11}(a)f_{13}(a))^{14} \\
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&= (a^{11}a^{13})^{14}
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&= (a^{24})^14
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&= a^{336}
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&\neq a^{2002}$
  
 
== See also ==
 
== See also ==
 
{{AMC10 box|year=2002|ab=P|num-b=11|num-a=13}}
 
{{AMC10 box|year=2002|ab=P|num-b=11|num-a=13}}
 
{{MAA Notice}}
 
{{MAA Notice}}

Revision as of 04:37, 15 July 2024

Problem 12

For $f_n(x)=x^n$ and $a \neq 1$ consider

$\text{I. } (f_{11}(a)f_{13}(a))^{14}$

$\text{II. } f_{11}(a)f_{13}(a)f_{14}(a)$

$\text{III. } (f_{11}(f_{13}(a)))^{14}$

$\text{IV. } f_{11}(f_{13}(f_{14}(a)))$

Which of these equal $f_{2002}(a)?$

$\text{(A) I and II only} \qquad \text{(B) II and III only} \qquad \text{(C) III and IV only} \qquad \text{(D) II, III, and IV only} \qquad \text{(E) all of them}$

Solution 1

We can solve this problem with a case by case check of $\text{I., II., III.,}$ and $\text{IV.}$ Since $f_n=x^n,$ $f_{2002}(a)=a^{2002}, all cases must equal$a^{2002}.$$ (Error compiling LaTeX. Unknown error_msg)\text{I. } (f_{11}(a)f_{13}(a))^{14}$$ (Error compiling LaTeX. Unknown error_msg)\begin{align*} (f_{11}(a)f_{13}(a))^{14} \\ &= (a^{11}a^{13})^{14} &= (a^{24})^14 &= a^{336} &\neq a^{2002}$

See also

2002 AMC 10P (ProblemsAnswer KeyResources)
Preceded by
Problem 11
Followed by
Problem 13
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 10 Problems and Solutions

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