00:01
All right, so number 13 brings up something that we were talking about already in numbers 1 through 12.
00:07
So if you didn't do numbers 1 through 12 or you didn't watch the videos, those can definitely answer this question.
00:13
But here's another way to go about it.
00:16
So when do you use parentheses when writing a solution in interval notation? well, you use parentheses whenever the boundary is not included in the solution set.
00:27
And whenever you write infinity or negative infinity in a solution set.
00:33
So i'm going to write the solution sets for each of these, and this will also apply to number 14.
00:39
The solution set for the first problem is we begin at 5, and we go to infinity.
00:48
For the second one, we begin at negative infinity, and we go all the way up to negative 2.
00:55
For the third, we start at negative 1, and we go all the way to positive infinity.
01:01
And for the last one, we start at negative infinity, and we go all the way up to seven.
01:09
So these match with the inequalities that i just came up with.
01:13
And we want to see which of these options do we use a parentheses instead of a bracket and maybe which parts of the options? because just seeing the symbol doesn't mean that you're going to for sure use one or the other.
01:26
It means you might use both.
01:30
So like i mentioned here, anytime you see infinity, you put open...