What is the derivative for sec^2? I am doing approximation problems.?

Question

Please i need help i have been studying for hours and i am just about ready to burn my calculus books.

Answer 1

y = sec^2(x)

You want to find dy/dx, correct? One thing to note is that
d/dx sec(x) = sec(x)tan(x). All we have to do is use the chain rule, since

y = [sec(x)]^2

dy/dx = 2[sec(x)] [sec(x)tan(x)]
dy/dx = 2sec^2(x)tan(x)

Answer 2

sec^2 x=(sec x)^2, use the chain rule

2(sec x)*((sec x)(tan x))