Difference between revisions of "2024 AMC 10B Problems/Problem 24"

(Problem 18)
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{{duplicate|[[2024 AMC 10B Problems/Problem 24|2024 AMC 10B #24]] and [[2024 AMC 12B Problems/Problem 18|2024 AMC 12B #18]]}}
 
 
 
==Problem==
 
==Problem==
 
Let
 
Let
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<math>\textbf{(A) } 0 \qquad\textbf{(B) } 1 \qquad\textbf{(C) } 2 \qquad\textbf{(D) } 3 \qquad\textbf{(E) } 4</math>
 
<math>\textbf{(A) } 0 \qquad\textbf{(B) } 1 \qquad\textbf{(C) } 2 \qquad\textbf{(D) } 3 \qquad\textbf{(E) } 4</math>
  
==Solution 1==
+
==Solution==
The first <math>20</math> terms <math>F_n = 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765</math>
 
 
 
so the answer is <math>1 +  3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =  \boxed{(B) 319} </math>.
 
 
 
~[https://artofproblemsolving.com/wiki/index.php/User:Cyantist luckuso]
 
 
 
==Solution 2==
 
 
 
Define new sequence <cmath>  G_n = \frac{F_{2n}}{F_{n}} = \frac{A^{2n} - B^{2n}}{A^{n} - B^{n}} =A^n+B^n </cmath>
 
 
 
A= <math>\frac{1+\sqrt{5}}{2}</math> and B = <math>\frac{1-\sqrt{5}}{2}</math>
 
 
 
Per characteristic equation, <math>G_n</math> itself is also Fibonacci type sequence with starting item <math>G_{1}=1 , G_{2}=3</math>
 
 
 
then we can calculate the first 10 items using <math>  G_{n}  =G_{n-1}  + G_{n-2} </math>
 
 
 
so the answer is <math>1 +  3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =  \boxed{(B) 319} </math>.
 
 
 
~[https://artofproblemsolving.com/wiki/index.php/User:Cyantist luckuso]
 
  
 
==See also==
 
==See also==
 
{{AMC10 box|year=2024|ab=B|num-b=23|num-a=25}}
 
{{AMC10 box|year=2024|ab=B|num-b=23|num-a=25}}
{{AMC12 box|year=2024|ab=B|num-b=17|num-a=19}}
 
 
{{MAA Notice}}
 
{{MAA Notice}}

Revision as of 05:54, 14 November 2024

Problem

Let \[P(m)=\frac{m}{2}+\frac{m^2}{4}+\frac{m^4}{8}+\frac{m^8}{8}\] How many of the values $P(2022)$, $P(2023)$, $P(2024)$, and $P(2025)$ are integers?

$\textbf{(A) } 0 \qquad\textbf{(B) } 1 \qquad\textbf{(C) } 2 \qquad\textbf{(D) } 3 \qquad\textbf{(E) } 4$

Solution

See also

2024 AMC 10B (ProblemsAnswer KeyResources)
Preceded by
Problem 23
Followed by
Problem 25
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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