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Hi all. Help with logarithmic differentiation please. 

 

Use logarithmic differentiation to find 

d/dx x^(2cos(x))

 Feb 29, 2016
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y =  x^(2cosx)

 

lny = lnx^(2cosx)

 

lny  = 2cosx* [ln x]       [ use the product rule to differentiate the right side ]

 

y' / y  =  -2sinx*lnx - 2cosx[ 1/x]

 

y' / y  =  [-2*x*sinx*lnx - 2cosx] / x         multiply both sides by y  [ and y = x^(2cosx)]

 

y ' =  x^(2cosx) * [ -2*x*sinx*lnx - 2cosx] * [x^(-1)]

 

y '  =  -2 * [ x^(2cosx)* x^(-1) ] [ x*lnx*sinx - cosx] 

 

y '  = -2 * [ x^(2cosx - 1) ] * [x*nx*sinx - cosx]

 

 

cool cool cool

 Feb 29, 2016

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