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Hello all,

I need to find the second order derivative of w by t, and to calculate it's value at t=1.

This is what I know about w, x and y.

\[w=ln(x+y)\]

\[x=e^{t}\]

\[y=e^{-t}\]

The answer in the book is:

\[\frac{4}{(e^{t}+e^{-t})^{2}}\]

I got another answer and I don't know what I did wrong, my solution is attached as an image.

Would appreciate your help with it. Thank you.

P.S According to Maple I am correct

I need to find the second order derivative of w by t, and to calculate it's value at t=1.

This is what I know about w, x and y.

\[w=ln(x+y)\]

\[x=e^{t}\]

\[y=e^{-t}\]

The answer in the book is:

\[\frac{4}{(e^{t}+e^{-t})^{2}}\]

I got another answer and I don't know what I did wrong, my solution is attached as an image.

Would appreciate your help with it. Thank you.

P.S According to Maple I am correct

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