document.write( "Question 352439: Find an equation of the tangent line at the point indicated. f (x) = log3 (8x + x^-8), x = 1? \n" ); document.write( "

Algebra.Com's Answer #251859 by Alan3354(69443) $\"\"$ $\"About$

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\n" ); document.write( "f (x) = $\"log%283%2C%288x+%2B+x%5E-8%29%29\"$ \r
\n" ); document.write( "\n" ); document.write( "f(x) = (1/ln(3))*ln(8x + x^-8)\r
\n" ); document.write( "\n" ); document.write( "f'(x) = (1/ln(3))*(1/(8x + x^-8))*(8 - 8x^-9)\r
\n" ); document.write( "\n" ); document.write( "@ x = 1: f'(x) = (1/ln(3))*(1/(8 + 1))*(8 - 8)
\n" ); document.write( "= 0\r
\n" ); document.write( "\n" ); document.write( "---------\r
\n" ); document.write( "\n" ); document.write( "f(1) = log(3,9) = 2\r
\n" ); document.write( "\n" ); document.write( "--> y = 2 is the line tangent at x = 1\r
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