D\dt in the higher derivative formula is an integer symbol, and a single d is meaningless, and neither is a single d\dt. D (one by one) /dt must appear, which means to take the derivative of the function in brackets and the derivative of the independent variable t.

The derivative of the first derivative is called the second derivative, and the derivatives above the second derivative can be defined step by step by induction. Derivatives of second order and above are collectively called higher order derivatives. Conceptually, the higher derivative can be calculated step by step through the operation rules of the first derivative, but considering the actual operation, this method is not feasible.

Extended data:

For the calculation of any n-order derivative, because n is not a definite value, it is naturally impossible to calculate it by step-by-step derivation. In addition, it is impossible to calculate the fixed-order derivative step by step when its order is high.

The so-called calculation of n-order derivative is actually trying to find the expression of derivative function with n as parameter. There is no general method to find the parameter expression of n-order derivative. The most common method is to find several derivatives according to the derivative calculation method, and then try to find out the regularity between them, and then deduce the parameter relationship of n.