What is e in mathematics and how much is it?

What is e in mathematics and how much is it?

Euler's formula for the base of natural logarithm, Yula was born in Switzerland in the 18th century. He lost his right eye sight at the age of 31 and his eyes were blind at the age of 59. However, he was optimistic and had amazing memory and concentration, EULA was modest all his life and never named what he found after himself. Only the base of the natural logarithm, which is about 2.71828, was named E. but because of his extensive contribution to mathematics, in many branches of mathematics, On the contrary, we often see important constants, formulas and theorems named after him. Many of the mathematical symbols we are used to now are invented and introduced by Yula, such as function symbols f (x), π, e, ∑, logx, SiNx, cosx, imaginary number I, etc, Help students remember a very special differential formula: in a mental hospital, a patient said to others all day, "I differentiate you, I differentiate you." I don't know why, these patients all have a little simple concept of calculus. They always think that one day they will be differentiated to zero and disappear like a polynomial function, so they can't avoid him, However, one day, he met a person who was not moved. He was very surprised, and this person said to him faintly, "I am the x power of E." the differential formula of x0d is: no matter how many times e differentiates x, the result is still e! No wonder mathematics students will use e to describe unswerving love! X0d is the first letter of circle in Greek characters relative to π, The origin of E is not well known. Some people even think that Yula takes the first letter of his name as the natural logarithm. There are two accepted reasons for Yula to choose e: first, after the four commonly used letters a, B, C, D, the first letter that has not been used is e. therefore, he naturally chose this symbol, It is the base of the natural logarithm; one is e, which is the first letter of the index. Although you may suspect that Yula, a Swiss, is not native to English, it is actually the index of French and German

What does e stand for?

E is the natural logarithm, commonly used as loge, denoted as LN, e = 2.71828183

The radius formula of circle

pir2

To expand a 20 kilometer long highway, it is necessary to widen 5 meters on both sides of the road. How many hectares has the area of this highway increased?
Please make a formula

5+5=10（m）
20km=20000m
20000 × 10 = 200000 square centimeters
200000 sq cm = 20 ha
By hand, I'm the first one to use
Kneel down! Kneel down!