Calculus Questions

Graph the solution set of x^2 +8x +12 (greater or equal to) 0.

At which values of x is f(x) = (x-4)/(x-2)(x+1) discontinuous?

Differentiate: y = (1+cos x)/(1-cos x).

Find an equation of the tangent line to the graph of x^2 + 3y^2 = 4 at the point (1,1).

Answering any of the above would be appreciated.