Infinity is a variable or function in which the absolute value of an independent variable increases infinitely during a certain change.

For example, f(x)= 1/x, which is infinite when x→0, and is denoted as lim( 1/x)=∞(x→0).

Infinity and infinitesimal have a reciprocal relationship, that is, when x→a is f(x) is infinite, 1/f(x) is infinitesimal.

Infinity is a mathematical symbol and a variable, which is denoted as ∞. Not all infinity are equal, they can even compare sizes:

Zero-order infinity: the number of all integers

First-order infinity: the number of all decimals (equal to all points on the straight line, all points on the surface and all points on the solid).

Two levels of infinity: draw any line on a piece of paper, and the number of all possible lines (the number of curve styles).

Zero order infinity

All infinity is equal to one of the above three.

Second-order infinity is the largest infinity known at present.

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