Positive infinity:

In the range of real numbers, it is a way to express a rational number or an irrational number greater than zero. There is no specific number, but positive infinity means a value greater than any number. The symbol is+∞.

A point on the number axis can be represented as an infinite arrow to the right.

When representing an interval, the negative infinity uses an open interval. For example, x∈( 1, +∞) means x >；; 1

Negative infinity:

A way that negative values represent infinitesimal. There is no specific number, but negative infinity means a value smaller than any number. The symbol is-∞.

A point on the number axis can be expressed as infinity to the left.

When representing an interval, the negative infinity uses an open interval. For example, x∈(-∞,-1) represents X.