# Domain

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• Today, we are learning how to find the domain of a fraction. This fraction will be our first example. The first step is to see of you can simplify your fraction anymore. This one is simplified as far as we can for now. Next, we will ignore the numerator of the fraction because we will only need to use the denominator to find the domain...
• Domain: 2x+1 ------------ (x^2)-9
• (x^2)-9
• Next, we'll take the x squared minus nine and factor it out into x plus three and x minus three. These factors cannot be passed by the graph so we will set each factor...
• This is great! I love this stuff!
• Ugh. I'm so bored.
• Domain: 2x+1 ------------ (x^2)-9
• ... not equal to zero. This means we will come up with the two domains of x does not equal negative three and x does not equal three. We will then put it in domain form by saying parenthesis, negative infinity, comma, negative three, close parenthesis, U, parenthesis, negative three, comma, three, close parenthesis, U, parenthesis, three, comma, infinity, close parenthesis. And there you have your answer.
• (x^2)-9 (x+3)(x-3) x≠-3 x≠3
• (-∞,-3)U(-3,3)U(3,∞)
• What the heck is she even saying? Is she speaking English? Did I accidentally walk into the German class again? Haha... That was a good moment...