welcome to Mumu Math and Science in this video let's talk about interval notation an interval notation is just a method for writing intervals on a number line Solutions can be written using brackets and parentheses for less than and greater than use parentheses for less than and equal to and greater than and equal to use brackets always use parentheses with infinity okay let's look at an example or two we have X is greater than three on the number line notice we have negative Infinity to the left positive Infinity to the right here's the three it's going to be open the arrow going to the right for Infinity I'm going to write from left to right so I'm going to go parentheses three comma Infinity parentheses next we have X is less than or equal to 2 okay okay here's negative Infinity positive Infinity the two is closed because it's includes the two because it's uh less than and equal to Arrow going to the left for Infinity right from left to right so I'm going to go parentheses negative Infinity comma 2 brackets and finally we have this example and it is -2 is less than or equal to X which is less than three if you'd like uh I like to rewrite this so I'm going to go X is greater than or equal to 2 and then excuse me -2 and X is less than three okay so here it is on the number line NE -2 is closed because it includes the -2 and three is open so I'm going to write it left to right okay bracket -2 comma three and then use parentheses because it's open I hope that was helpful thanks for [Music] watching