I'm having trouble solving this problem. I have to find the equation of a line tangent to a curve at a specific point. I also have to use a certain technique.

The curve is:

f(x) = x^2+2x+3

The point to be tangent to is:

P = (-1, 6)

I have to use these equations to solve.

m(tan) = lim(x->c) (f(x) - f(c))/(x-c))

and

y - f(c) = m(tan)(x - c)

I can get to the point where I have (x^2 - 2x) / (x+1). I'm not sure how to proceed. Thanks