In the study of Differential Calculus, in general, the first application of limit that we learn allows us to obtain the equation of the tangent line to the graph of a given function f at a point P(x,y). This concept known as Derivative has numerous applications that allow us to measure rates of variation, such as speed, acceleration, growth, decrease, etc. Thus, consider f(x) = x2 a real function defined on every line R, determine the equation of the tangent line to this curve at the point P(2,4).