Difference between revisions of "2015 AMC 12B Problems/Problem 8"

(Problem)
(Solution)
Line 5: Line 5:
  
 
==Solution==
 
==Solution==
 
+
<math>(625^{\log_5 2015})^\frac{1}{4}
 +
= ((5^4)^{\log_5 2015})^\frac{1}{4}
 +
= (5^{4 \cdot \log_5 2015})^\frac{1}{4}
 +
= (5^{\log_5 2015 \cdot 4})^\frac{1}{4}
 +
= ((5^{\log_5 2015})^4)^\frac{1}{4}
 +
= (2015^4)^\frac{1}{4}
 +
= \boxed{\textbf{(D)}\; 2015}</math>
  
 
==See Also==
 
==See Also==
 
{{AMC12 box|year=2015|ab=B|num-a=9|num-b=7}}
 
{{AMC12 box|year=2015|ab=B|num-a=9|num-b=7}}
 
{{MAA Notice}}
 
{{MAA Notice}}

Revision as of 23:29, 3 March 2015

Problem

What is the value of $(625^{\log_5 2015})^{\frac{1}{4}}$ ?

$\textbf{(A)}\; 5 \qquad\textbf{(B)}\; \sqrt[4]{2015} \qquad\textbf{(C)}\; 625 \qquad\textbf{(D)}\; 2015 \qquad\textbf{(E)}\; \sqrt[4]{5^{2015}}$

Solution

$(625^{\log_5 2015})^\frac{1}{4} = ((5^4)^{\log_5 2015})^\frac{1}{4} = (5^{4 \cdot \log_5 2015})^\frac{1}{4} = (5^{\log_5 2015 \cdot 4})^\frac{1}{4} = ((5^{\log_5 2015})^4)^\frac{1}{4} = (2015^4)^\frac{1}{4} = \boxed{\textbf{(D)}\; 2015}$

See Also

2015 AMC 12B (ProblemsAnswer KeyResources)
Preceded by
Problem 7
Followed by
Problem 9
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