Find an equation of the tangent line to the curve $y = x\cos(x)$ at the point $(\pi, -\pi)$ I concluded that the equation is
$$(y + \pi) = (\cos(x) + x-\sin(x)) (x - \pi)$$
1) Is this correct so far?  Wolfram doesn't seem to process this correctly.
2) How would I expand this to get it in $y$-intercept form? I know I can plug $\pi$ into my derivative, but i'm not sure what to make of plugging $x$ into it. I feel like it wouldn't be correct, or it would be correct but it would be so verbose the data would be unusable. 

Your gradient of the tangent line is not correct.
Step 1. Differentiate $y=x\cos x$. $y'=\cos x-x\sin x$.
Step 2. Find the gradient of the tangent line by putting $x=\pi$ into $y'$; thus $m=-1$.
Step 3. Write the equation of the line in the form $y-y_0=m(x-x_0)$; thus $y+\pi=-1(x-\pi)$ (or $y=-x$)
To find the $y$-intercept, you put $x=0$, so $A(0,0)$ is your $y$-intercept.
