1 has different meanings: the infinite observation background is the process, and the judgment premise of unbounded variables is the interval.

2. Different meanings: the names of infinitesimal and infinitesimal imply their development trend (in a specific process); An unbounded variable means that there is no upper bound on its absolute value in a certain interval.

Mathematical operation of infinity:

In advanced mathematics, it is stipulated that x is a real number, when x >; 0，x÷0 =+∞； When x is less than 0, x ÷ 0 =-∞; When x=0, x÷0 is meaningless.

The addition, subtraction, multiplication, division, power and square root of positive infinity and real numbers always result in positive infinity; The addition, subtraction, multiplication, division, multiplication and root sign of negative infinity and real numbers always produce negative infinity. (0 ×∞ meaningless)

In a sense, +∞ can be expressed as X+ 1, because x is the symbol of any real number or imaginary number, and ∞ must be greater than any real number or imaginary number. The paradox of 0.999…999(0.9 infinite loop) = 1 shows that infinity may be infinite enough to contain a higher level.