Question

How do you differentiate `f(x)=1/sinx-secx+tanx` using the sum rule?

Answer 1

Rewrite `f(x)=csc(x)-sec(x)+tan(x)`
`f'(x)=-csc(x)cot(x)-sec(x)tan(x)+sec^2(x)`

Explanation:

The sum rule just indicates that since you are differentiating terms that are added or subtracted you can differentiate term by term.
`(d/dx)[f(x)+g(x)]=f'(x)+g'(x)`