What would it be?

Question

x <= - 5oRx >= 9

what is the interval notation?

Answer 1

x < -5 or x > 9

(-inf, -5] U [9, inf)

use [ or ], brackets to indicate the interval includes the end point

use parentheses to indicate the interval does not include the end point

infinity is not a real number. It is only a limit that is approached but never reached.

It's sometimes called a "surreal" number.

"U" means Union of sets. The sets are the two intervals

Answer 2

(- ∞, - 5] U [9, ∞)

Answer 3

Since x must be less than or equal to -5 it can be -10 or -100 or -1,000.000. So we can say it is between negative infinity and -5. Since it CAN BE -5, we use a square bracket next to "-5". But negative infinity is not a number so we use a parenthesis "(" next to it like this: (-∞, -5].

For the other portion, it is [9, ∞).

Putting both of these together means we are taking the "union" of both sets and "union" is denoted as "U" so the answer is:

(-∞, -5] U [9, ∞)