\(y = \tan x - 2{x^3}\)

Câu hỏi: \(y = \tan x - 2{x^3}\)

A \(y' =- \dfrac{1}{{{{\cos }^2}x}} - 6{x^2}\)

B \(y' =- \dfrac{1}{{{{\cos }^2}x}} + 6{x^2}\)

C \(y' = \dfrac{1}{{{{\cos }^2}x}} - 6{x^2}\)

D \(y' = \dfrac{1}{{{{\cos }^2}x}} + 6{x^2}\)