So the title is a bit vague, let me clarify.
I was trying to find the derivative of $\frac {x}{cos(x)}$
I figured, to avoid using the quotient rule I will just write it as $x*sec(x)$ which is easy to figure out using the product rule. So I got: $xsec(x)tan(x)+sec(x)$. When trying the quotient rule I get: $\frac {xsin(x)+cos(x)}{cos^2(x)}$. What am I not getting here? Thanks in Advance!
They're the same expression. Look at this plot here on desmos and you will see that they have the same plot.
To show this multiply the $x\tan x \sec x + \sec x$ expression by $\frac{\cos^2 x}{\cos^2 x}$.