Question

f(x)=tanx-1/secx

Answer 1

$f(x)=\dfrac{\tan x-1}{\sec x}$

$f(x)=\dfrac{\dfrac{\sin x}{\cos x}-1}{\dfrac{1}{\cos x}}$

$f(x)=\sin x-\cos x$

Differentiating the above equation

$\dfrac{d[f(x)]}{dx}=\cos x+\sin x$

$f'(x)=\sin x+\cos x$