document.write( "Question 407756: (e^2x)-(2e^x)-15=0 \n" ); document.write( "
Algebra.Com's Answer #287348 by lwsshak3(11628)\"\" \"About 
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(e^2x)-(2e^x)-15=0\r
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\n" ); document.write( "\n" ); document.write( "(e^2x)-(2e^x)-15=0
\n" ); document.write( "let u=e^x
\n" ); document.write( "then u^2=e^2x
\n" ); document.write( "we then have a quadratic equation
\n" ); document.write( "u^2-2u-15=0
\n" ); document.write( "(u-5)(u+3)=0
\n" ); document.write( "u-5=0
\n" ); document.write( "u=5
\n" ); document.write( "u+3=0
\n" ); document.write( "u=-3
\n" ); document.write( "u=e^x=5
\n" ); document.write( "xlne=ln5
\n" ); document.write( "x=ln5=1.609
\n" ); document.write( "..
\n" ); document.write( "u=e^x=-3(reject, an exponential function is always>0)
\n" ); document.write( "solution: x=1.609\r
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