Infinity Symbol. In so-called interval notation, the same function has a domain of This describes the set of values from 0 to positive infinity. (Saying that the limit equals $\infty$ or $-\infty$ is not saying that the limit exists, it is saying that the limit does not exist and explaining why: because the values of the function grow without bound, either in the positive direction or in the negative direction, respectively). It is also possible to have infinite intervals. The infinity symbol is a mathematical symbol that represents an infinitely large number. Therefore, both positive and negative infinity will ALWAYS use parenthesis (). The dots (or ellipsis) mean that the number of terms are infinite.. Obviously, if you have an infinite number of terms, it would be impossible to actually write out those terms (it would take you an infinite amount of time! That is because for inequalities with one value and with the "greater than" symbol (such as x > 9), there are an infinite amount of positive … For (negative infinity, 1), let's say I choose x = 0; then y = 0 – 0 + 2 = 2, which is positive. Use parentheses to represent infinity or negative infinity, since positive and negative infinity are not numbers in the usual sense of the word and, therefore, cannot be “equaled.” ... Set Indicated Set-Builder Notation Interval Notation; All real numbers between a and b, but not including a or b [latex]\{x|a