# PreCalculus Project

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#### Storyboard Description

my precal project about determining the domain of a function

#### Storyboard Text

• Zoe is waiting for her colleague to arrive in front of a cafe.﻿
• Hmm, where is he?﻿ I need him to guide and mentor me as I will be taking his place in the Pre-Calculus class!
• Oh, there you are, Mr. Grekins!﻿ Where were you?
• My apologies, dear Zoe. I had a class to teach. I taught them a new lesson which was about finding the domains of a function.﻿ Let's enter, shall we?
• Examples: - f(x) = 1 / x﻿2- x  : Domain: {x | x ≠﻿ 1} - f(x) = √9-x2  : Domain: {x | -3 < x < 3} - f(x) = x / √x+1   Domain: {x > -1}
• ﻿To start with, the domain of a function is the set of x-values that you can put into the function. It is an input value in order to produce an output value (range).
• ﻿So, tell me. The lesson was about finding the domains of a function. What can you say about that?
• Yes, of course! The basic rules are that if the function is radical, the radicand cannot be negative. For instance, if the function is the square root of x, x cannot be negative. Thus, the domain will be {x | x > 0}.
• Ah.. that's interesting. Can you tell me the rules?
• On the other hand, if the function is a fraction, the denominator cannot be zero. For instance, if the function is 1/x, x cannot be zero. Thus, the domain will be {x | x ≠ ﻿0}. If the function is a normal polynomial with no radical or fraction, the domain can be all real numbers, which is {x | x = |R}.
• Wow! I hope to be like you someday, Mr. Gekins. Will you show me your class?
• As Mr. Gekins show Zoe his class, Zoe couldn't wait to start teaching!
• ﻿Pre-Calculus Lesson: Finding The Domain of A Function
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