2. We use δ to represent finite increment. For example, delta x is a finite increment of x, which is pronounced delta.
x；
3. When the increment is infinite, we will write dx, dy, dz, etc.
4.dy/dx is the ratio of two infinitesimal increments. We call it derivative, which was translated into "WeChat business" in early years, which is very vivid;
5. dx in the integral is still an infinitesimal, which is the bottom width of the slender rectangle, and f(x) is the height of the rectangle.
F(x)dx is the volume of this slender rectangle, which we call volume element;
6. In some books, dx is written as δx, which means the same thing. Because the fourth letter of Greek is capitalized.
Is delta, lowercase is delta, d is the fourth lowercase letter in English, and d means English is differential.
It's a derivative, a differential. In English, derivative and differential are indistinguishable; There is no difference in differentiability.
Yes, it is differentiable. Chinese translation is divided into derivative and differential, derivative and differentiability.
This is the progress of Chinese, but there are many things in Chinese that cannot be expressed. This will
Hurt the national pride of many of us.
7. In multivariate function, d in dz/dx becomes? z/？ 10. The meaning hasn't changed at all, just complicated.
Just a dot? Reading part.