Question

How do you find the derivative of `y = 4 / cosx`?

Answer 1

`4 sec x tan x`

Explanation:

`( 4 / cosx)' = 4 (( cosx)^{-1} )'`

`= 4 (-1( cosx)^{-2} (-sin x))`

`= 4 (1/( cosx)^{2} (sin x))`

`= 4 sec x tan x`