Difference between revisions of "2016 AMC 10A Problems/Problem 2"

m (Added 12A box for matching question)
m (Solution)
Line 8: Line 8:
  
 
We can rewrite <math>10^{x}\cdot 100^{2x}=1000^{5}</math> as <math>10^{5x}=10^{15}</math>:
 
We can rewrite <math>10^{x}\cdot 100^{2x}=1000^{5}</math> as <math>10^{5x}=10^{15}</math>:
<cmath>10^x\cdot100^{2x}=10^x\cdot(10^2)^{2x}</cmath>
+
<cmath>\begin{split}
<cmath>10^x\cdot10^{4x}=(10^3)^5</cmath>
+
10^x\cdot100^{2x} & =10^x\cdot(10^2)^{2x} \\
<cmath>10^{5x}=10^{15}</cmath>
+
10^x\cdot10^{4x} & =(10^3)^5 \\
Since the bases are equal, we can set the exponents equal: <math>5x=15</math>. Solving gives us: <math>x = \boxed{\textbf{(C)}\;3.}</math>
+
10^{5x} & =10^{15}
 +
\end{split}</cmath>
 +
Since the bases are equal, we can set the exponents equal, giving us <math>5x=15</math>. Solving the equation gives us <math>x = \boxed{\textbf{(C)}\;3}.</math>
  
 
==See Also==
 
==See Also==

Revision as of 16:43, 17 February 2016

Problem

For what value of $x$ does $10^{x}\cdot 100^{2x}=1000^{5}$?

$\textbf{(A)}\ 1 \qquad\textbf{(B)}\ 2\qquad\textbf{(C)}\ 3\qquad\textbf{(D)}\ 4\qquad\textbf{(E)}\ 5$

Solution

We can rewrite $10^{x}\cdot 100^{2x}=1000^{5}$ as $10^{5x}=10^{15}$: \[\begin{split} 10^x\cdot100^{2x} & =10^x\cdot(10^2)^{2x} \\ 10^x\cdot10^{4x} & =(10^3)^5 \\ 10^{5x} & =10^{15} \end{split}\] Since the bases are equal, we can set the exponents equal, giving us $5x=15$. Solving the equation gives us $x = \boxed{\textbf{(C)}\;3}.$

See Also

2016 AMC 10A (ProblemsAnswer KeyResources)
Preceded by
Problem 1
Followed by
Problem 3
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
2016 AMC 12A (ProblemsAnswer KeyResources)
Preceded by
Problem 1
Followed by
Problem 3
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