f(x) = [ lnx + log2 x ] / [tanx] =
lnx / tanx + log2 x / tanx using the Quotient Rule on both, we have
[ (1/x) * tanx - lnx * sec^2 x] / [tan^2 x] + [ 1 / [x ln 2] * tanx - log2 x * sec^2x] / [tan^2x] =
[ tanx/x - lnx * [tan^2 x + 1] / [tan^2 x] + ( [ tanx/ [ x ln2] - log2 x [ 1 + tan^2x] ) / [tan^2 x] =
[ tanx ( 1/x + 1/[ x ln2] ) - [ tan^2x + 1] ( lnx + log2 x ) ] / [ tan^2 x] =
[ ln 2 + 1] / [ x* ln2 * tanx] - [ sec^2x / tan^2x] * (lnx + log2 x) =
[ ln 2 + 1] / [ x* ln2 * tanx] - csc^2x * (ln x + log2 x ) =
[ln2 + 1] * cot x / [x ln 2] - csc^2x (ln x + log2 x)