tolong di bantu ya :)

1.
Tadi udah dijawab ya,

2.
[tex]\displaystyle f(x)=\ln(\frac{1-e^x}{1+e^x}) \\ f'(x)=\ln'(\frac{1-e^x}{1+e^x})\times(\frac{1-e^x}{1+e^x})' \\ f'(x)=\frac{1+e^x}{1-e^x}\times \frac{-e^x(1+e^x)-e^x(1-e^x)}{(1+e^x)^2} \\ f'(x)=\frac{1+e^x}{1-e^x}\times \frac{-e^x-e^{2x}-e^x+e^{2x}}{(1+e^x)^2} \\ f'(x)=\frac{-2e^x}{(1-e^x)(1+e^x)} \\ f'(x)=\frac{-2e^x}{1-e^{2x}}[/tex]

3.
[tex]f(x)=(\cos x)^{\sin x} \\ f(x)=(e^{\ln \cos x})^{\sin x} \\ f'(x)=e^{\sin x\ln(\cos x)}\times (\sin x \ln \cos x)' \\ f'(x)=(\cos x)^{\sin x}\times (\cos x \ln (\cos x) + \sin x \times\ln(\cos x)') \\ f'(x)=(\cos x)^{\sin x}\times (\cos x \ln (\cos x) + \sin x \times\frac{1}{\cos x}\times-\sin x) \\ f'(x)=(\cos x)^{\sin x}\times (\cos x \ln (\cos x) - \sin x\tan x)[/tex]

4.
Sebetulnya saya masih kurang paham dengan maksud soalnya...
Kalo gak salah,
[tex]\ln(xy)=ye^x+3xy^2 \\ (\ln(xy))'=(ye^x)'+(3xy^2)' \\ \frac{1}{xy}\times y=ye^x+3y^2 \\ \frac{1}{x}=ye^x+3y^2[/tex]