Question

Why second differntiation negative called maximum point?

Answer 1

Second differentiation negative means that the rate of change of slope of that function in that particular interval is decreasing which implies that if we move the tangent from a point just left to the point of maxima to a point just right to the point of maxima, it decreases from a positive value to zero to some negative value. Hence the point where it becomes zero is the point of maxima. Looking at the graph can help you better. Hope this helps:)