Hi, I am having trouble getting equation to tangent lines for functions, I compute the derivative first but then don't have a clue what to do after, or where to plug in/substitute the specified values. Here are the exact directions:

Find the equation of the line that is tangent to the graph of the given function at the specified point.

Y= -X^3 - 5X^2 + 3X - 1 ; (-1,-8)

The answer is Y= 10X + 2

Also another question, I don't know if I use the same technique as the above to answer it. Instructions: Find all points on the graph of the given function where the tangent line is horizontal.

F(X)= (X+1)(X^2-X-2)

Answer is (1,-4) , (-1,0)

Thanks for the help