Find f'(x).

f(x) = 3 ln x + ln x8 + 7ex

assuming you meant

f(x) = 3 ln x + ln x^8 + 7e^x
then that's the same as
f(x) = 3 lnx + 8 lnx + 7e^x
f(x) = 11 lnx + 7e^x
so
f'(x) = 11/x + 7e^x