Differentiate the following equation

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Homework Statement



Differentiate

s = Tan ^{2}(e^{4t})



Homework Equations



[e^{u}]' = u' e^{u}

[Tan(θ)]' = Sec^{2}(θ)

Sec(θ) = \frac{1}{Cos(θ)}



The Attempt at a Solution



s' = 2[Tan(e^{4t})] * Sec^{2}(e^{4t}) * 4e^{4t}

s' = 8e^{4t} * Tan(e^{4t}) * Sec^{2}(e^{4t})

s' = 8e^{4t} * \frac{Tan(e^(4t))}{Cos^2(e^(4t))}



Mathway says that s' = 0... Can someone please let me know where I went wrong? Thanks
 
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You're derivative is right. Are you sure they didn't ask you to evaluate the derivative at some point? I'm guessing that they want you to evaluate it at 0.
 
Yes, you're right, I have to find s'(0) aka v(0)

I end up getting this:

v(0) = 8e^{0} * \frac{Tan(e^0)}{Cos^2(e^0)}

v(0) = 8 * \frac{Tan(1)}{Cos^2(1)}

Is that good?
 
Blablablabla said:
Yes, you're right, I have to find s'(0) aka v(0)

I end up getting this:

v(0) = 8e^{0} * \frac{Tan(e^0)}{Cos^2(e^0)}

v(0) = 8 * \frac{Tan(1)}{Cos^2(1)}

Is that good?

Yes, it is.
 
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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