when the nature is max?
+ve to -ve
when nature is minimum?
-ve to +ve
when nature is max for two turning points?
< 0
less than 0
when nature is min for two turning points?
> 0
more than 0
differentiation from first principle
dy/dx = x+h -x/ h
what is the derivative of tan (x) ?
sec^2 (x)