# What is the difference between a finite interval and an infinite interval?Which of the following intervals are finite and why? 1. ( a, ∞) 2. (1, 1.4] 3. (-∞ ,∞)

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For instance, the first interval is finite on the left side and infinite to the right side.

Why?

Because, the left end of the interval is a real number, since the right end is a symbol, and not a value.

The real set of number contains also the symbols infinite and -infinite, but they are not real values.

The second interval (1, 1.4] is also finite, since both ends are real values. This interval is opened to the left side and closed to the right. That means that the value 1 is not included but is included.

**The 3rd interval is the real set of numbers, that is infinite.**

**(-∞ ,∞) = R**