Difference between revisions of "2007 Cyprus MO/Lyceum/Problem 2"

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==Solution==
 
==Solution==
<math>f(x+1)-f(x)=4^{x+1}-4^x=4\cdot4^x-4^x=(4-1)\cdot4^x=3\cdot4^x\Rightarrow\mathrm{ E}</math>
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<math>f(x+1)-f(x)=4^{x+1}-4^x=4\cdot4^x-4^x=(4-1)\cdot4^x=3\cdot4^x\Longrightarrow\mathrm{ E}</math>
  
 
==See also==
 
==See also==
*[[2007 Cyprus MO/Lyceum/Problems]]
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{{CYMO box|year=2007|l=Lyceum|num-b=1|num-a=3}}
  
*[[2007 Cyprus MO/Lyceum/Problem 1|Previous Problem]]
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[[Category:Introductory Algebra Problems]]
 
 
*[[2007 Cyprus MO/Lyceum/Problem 3|Next Problem]]
 

Latest revision as of 19:30, 6 May 2007

Problem

Given the formula $f(x) = 4^x$, then $f(x+1)-f(x)$ equals to

$\mathrm{(A) \ } 4\qquad \mathrm{(B) \ } 4^x\qquad \mathrm{(C) \ } 2\cdot4^x\qquad \mathrm{(D) \ } 4^{x+1}\qquad \mathrm{(E) \ } 3\cdot4^x$

Solution

$f(x+1)-f(x)=4^{x+1}-4^x=4\cdot4^x-4^x=(4-1)\cdot4^x=3\cdot4^x\Longrightarrow\mathrm{ E}$

See also

2007 Cyprus MO, Lyceum (Problems)
Preceded by
Problem 1
Followed by
Problem 3
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