Question

what is meant by the process of differentiation

Answer 1

The essence of calculus is the derivative. The derivative is the instantaneous rate of change of a function with respect to one of its variables. This is equivalent to finding the slope of the tangent line to the function at a point. Let's use the view of derivatives as tangents to motivate a geometric definition of the derivative. 
 We want to find the slope of the tangent line to a graph at the pointP. We can approximate the slope by drawing a line through the point P and another point nearby, and then finding the slope of that line, called a secant line. The slope of a line is determined using the following formula (mrepresents slope) :



 Let P = (x,y) and Q := (a,b). Let



Then the slope of the line



Answer 2

It means to take differences from the both things you are differentiating and write them in a table