Trig derivative? f(x)=6arctan(7e^x)

if f(x)=6arctan(7e^x) then how do you find the derivative? please help

e^x/(7e^2x/6+1/42)

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ans: 42e^x/(1 + 49e^2x)
d(f(x)/dx=d(6arctan(7e^x))/d(7e^x) x d(7e^x)/dx
=6/(1+49e^2x) x 7e^x
=42e^x/(1 + 49e^2x)