Equation of Tangent Line to y=(lnx)^cosx at (pi/2,1)

dvaughn
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Find the equation of the tangent line to the curve y=(lnx)^cosx at the point (pi/2, 1)?

The Attempt at a Solution


lny = cosx(ln(ln(x))) d/dx
= -sinx(ln(ln(x))) + cosx/(ln(x)(x))
y' = y(-sinx(ln(ln(x))) + cosx/(ln(x)(x)))
this is the part where I get stuck
 
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dvaughn said:
Find the equation of the tangent line to the curve y=(lnx)^cosx at the point (pi/2, 1)?

The Attempt at a Solution


lny = cosx(ln(ln(x))) d/dx
= -sinx(ln(ln(x))) + cosx/(ln(x)(x))
y' = y(-sinx(ln(ln(x))) + cosx/(ln(x)(x)))
this is the part where I get stuck

When you get to
y'=y\left[ {\frac{\cos\left(x\right)}{x\ln\left(x\right)}-\sin\left(x\right)\ln\left(\ln\left(x\right)\right)}\right]
substitute \ln\left(x\right)^{\cos\left(x\right)} for y.

Then take y'\left(\frac{\pi}{2}\right) as the slope of your tangent line and find what y-intercept will put the line through \left(\frac{\pi}{2},1\right).
 
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There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...

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