document.write( "Question 201539: Listed below are 5 functions each denoted g(x) and each involving a real number
\n" ); document.write( " x
\n" ); document.write( "constant c>1. If f(x)=2 , which of these 5 functions yeilds the greatest value for f(g(x)), for all x>1?\r
\n" ); document.write( "\n" ); document.write( "A. g(x)= cx
\n" ); document.write( "B. g(x)= c/x
\n" ); document.write( "C. g(x)= x/c
\n" ); document.write( "D. g(x)= x-c
\n" ); document.write( "E. g(x)= log x
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Algebra.Com's Answer #151892 by jsmallt9(3758)\"\" \"About 
You can put this solution on YOUR website!
\"f%28x%29+=+2%5Ex\" means this function will take whatever you give it and raise 2 to that power. So when we give it g(x) it will raise 2 to that power: \"f%28g%28x%29%29+=+2%5E%28%28g%28x%29%29%29\"

\n" ); document.write( "So now we can see what will happen to this for the various definitions of g(x).
\n" ); document.write( "A. g(x)= cx
\n" ); document.write( "\"f%28cx%29+=+2%5E%28cx%29\"
\n" ); document.write( "B. g(x)= c/x
\n" ); document.write( "\"f%28c%2Fx%29+=+2%5E%28c%2Fx%29+=+2%5E%28c%2A%281%2Fx%29%29\"
\n" ); document.write( "C. g(x)= x/c
\n" ); document.write( "\"f%28x%2Fc%29+=+2%5E%28x%2Fc%29+=+2%5E%28x%2A%281%2Fc%29%29\"
\n" ); document.write( "D. g(x)= x-c
\n" ); document.write( "\"f%28x-c%29+=+2%5E%28%28x-c%29%29\"
\n" ); document.write( "E. g(x)= log x
\n" ); document.write( "\"f%28log%28%28x%29%29%29+=+2%5E%28log%28%28x%29%29%29\"

\n" ); document.write( "Now we just need to figure out which exponent is largest
\n" ); document.write( "When c>1 and x>1 ...
\n" ); document.write( "A. cx > x and cx > c
\n" ); document.write( "B. 1/x is between 0 and 1 so c*(1/x) < c.
\n" ); document.write( "C. 1/c is between 0 and 1 so x*(1/c) < x.
\n" ); document.write( "D. x-c < x
\n" ); document.write( "E. log(x) < x. This is the trickiest one to explain. If you look at graphs of y=x and y=log(x) superimposed on each other you will see that for all x-values the graph of graph of y=log(x) is below the graph of y=x. So log(x) < x for all x. (Unfortunately I can't get Algebra.com software to graph log(x). If I could I'd show you these graphs here.)

\n" ); document.write( "In summary, when c>1 and x>1 only c*x is guaranteed to be larger than both c and x. So c*x is the largest exponent which means \"2%5E%28cx%29\" is the largest which means the answer is A.
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