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Use logarithmic differentiation to find the derivative of the function: `y = (sin...

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frdsmith | Student, Grade 11 | eNoter

Posted March 8, 2012 at 1:45 PM via web

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Use logarithmic differentiation to find the derivative of the function: `y = (sin 9x)^(lnx)`

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted March 8, 2012 at 2:15 PM (Answer #1)

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The derivative of `y=(sin 9x)^(ln x)` has to be determined.

`y=(sin 9x)^(ln x)`

take the natural logarithm of both the sides

`ln y = ln((sin 9x)^(ln x))`

=> `ln y = ln x*ln(sin 9x)`

Take the derivative

`(y')/y = (1/x)*ln(sin 9x) +(ln x*9cos 9x)/(sin 9x)`

=> `y' = y((1/x)*ln(sin 9x) + (ln x*9cos 9x)/(sin 9x))`

=> `y' = (sin 9x)^ln x*(ln(sin 9x)/x + (9cos 9x*ln x)/(sin 9x))`

The derivative `y' = (sin 9x)^(ln x)(ln(sin 9x)/x + (9cos 9x*ln x)/(sin 9x))`

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