How to find slope & Tangent line

Finding Slope and Tangent line : To find the equation of the tangent line for the curve y = f(x) at a given point (a, f(a)): let us consider another point q ((a+h), f(a+h)) slope of the secant line passing through p and q is f(a+h) - f(a) / h as q approaches p, making h smaller and the difference quotient should approach a certain limiting value m, which is the slope of the tangent line at the point p. If m is known then the equation of the tangent line is given by (y - f(a) ) = m (x - a)