The natural logarithm of the exponent is equal to. Natural logarithm, function ln x

Rice. 16. Behavior of the function f(x) = x4 4x3

When passing through the point x = 0, the derivative does not change sign: the function decreases both on the interval (1; 0] and on the interval. Therefore, the point x = 0 is a saddle point of the function.

But when passing through the point x = 3, the derivative changes sign from () to (+). In between)