Quick lookup table for a few common derivatives.
d(x^n)/dx = n * x^(n-1)
d(e^x)/dx = e^x
d(a^x) = a^x * log(a)
d(lnx)/dx = 1/x
(f + g)' = f' + g'
(f * g)' = f' * g + f * g'
(f/g)' = (f' * g - f * g') / g^2