Why you should NOT use second derivative test to determine local max|min and what to do instead

In differential calculus, how do you tell if a critical point is a local max, local min, or inflection point? What is the best way to classify critical points? Students often use the 2nd derivative test to classify critical points, especially in high school calculus. I do not recommend the second derivative test because there are cases when the second derivative test fails. I will give you an example to illustrate it and show you what to do if the second derivative test is inconclusive.

0:26 - a quick recap of what critical points are
1:40 - an example of when the second derivative test fails

2nd derivative test fails,calculus 2nd derivative test,calculus second derivative,2nd derivative,common calculus mistakes,first derivative test,local max and min calculus,why second derivatives fail,what to do if second derivative test fails,mcv4u,what if second derivative test fails,how to classify critical points,calculus second derivative test,concavity,how to test critical points,khan academy,derivatives calculus,second derivative test fails,