Use the method in Example 3 to find 

(a) The slope of the curve at the given point P, and 

(b) An equation of the tangent line at P.

y = x² - 2x - 3, P(2, -3)

Example 3

Find the slope of the parabola y = x² at the point P(2, 4). Write an equation for the tangent to the parabola at this point.