Like what you saw?
Create FREE Account and:
 Watch all FREE content in 21 subjects(388 videos for 23 hours)
 FREE advice on how to get better grades at school from an expert
 FREE study tips and eBooks on various topics
Graphing Radical Equations using a Table  Problem 2
Alissa Fong
Alissa Fong
MA, Stanford University
Teaching in the San Francisco Bay Area
Alissa is currently a teacher in the San Francisco Bay Area and Brightstorm users love her clear, concise explanations of tough concepts
When I want to find the domain of a radical function the most important thing to keep in mind is that the radicand cannot be negative. The stuff under the square root has to be greater than or equal to 0. That’s how to find the domain.
Look at this stuff under the square root it’s the quantity x plus 1. I don’t care about that minus 2 business because that’s not under the square root, my domain comes from this inequality. I got to find x values that are going to be greater than or equal to 1. That’s my domain. Any x value I substitute in to my function that’s greater than or equal to negative 1, would give me a real solution. If I chose like 2, I would get a non real solution I’d have the square root of a negative number and that doesn’t make much sense.
Okay so what I’m going to do is make my x/y chart using x numbers that are bigger than or equal to 1. You have to be really careful when you substitute them in that you follow the order of operations. You're going to add one first, square root that result then subtract 2. So let’s do a couple together.
If I take 1 for my x number 1 plus 1 is 0, square root of 0 is 0 and then take way 2. Careful with order of operations, 0 plus 1 is 1, square root is 1 is 1 take away 2. 1 plus 1 is 2 square root of 2 is 1.4 and then I have to do 1.4 take away 2 and you get .58 I think. You can double check that on your calculator, be really careful with the order of operations. If I do 2 plus 1 there that’s 3, square root of 3 is 1.7 then I have to do 1.7 take away 2 and I get .26.
Last but not least 3 plus 1 is 4, the square root of 4 is 2, 2 take away 2 is 0. Okay so I have my bunch of good points that I chose using my domain I’m going to get these guys on the graph. My first point is going to be (1,2), then I have (0,1), (1,.58) I’m just going to approximate like around to halfish and then (2,.26) and then (3,0). Those are the points from my graph.
You can see how the shape is starting to come together, be really careful that I don’t put an arrow on that side, it’s a dead end that ends with that closed circle at (1,2). It does however have an arrow on this side because my domain continues to all x values that are greater than or equal to 1.
Once you have that set up you guys are ready to go, you have your graph, you’re a happy camper just make sure when you are doing these tables you are really careful with the order of operations. Substitute your x value into the radicand which is under the square root, take the square root before you do any additional adding or subtracting.
Please enter your name.
Are you sure you want to delete this comment?
Alissa Fong
M.A. in Secondary Mathematics, Stanford University
B.S., Stanford University
Alissa has a quirky sense of humor and a relatable personality that make it easy for students to pay attention and understand the material. She has all the math tips and tricks students are looking for.
Your tutorials are good and you have a personality as well. I hope you have more advanced college level stuff, because I like the way you teach.”
Thanks alot for such great lectures... I never found learning this easier ever before... keep up the great work.... :)”
You seem so kind, it's awesome. Easier to learn from people who seem to be rooting for ya!' thanks”
Sample Problems (5)
Need help with a problem?
Watch expert teachers solve similar problems.

Graphing Radical Equations using a Table
Problem 1 3,227 viewsFind the domain of f(x) = √x + 4 and sketch a graph using a table of values.

Graphing Radical Equations using a Table
Problem 2 3,045 viewsFind the domain of f(x) = √x + 1 − 2 and sketch a graph using a table of values.

Graphing Radical Equations using a Table
Problem 3 2,434 viewsFind the domain of f(x) = √2x + 1 and sketch a graph using a table of values.

Graphing Radical Equations using a Table
Problem 4 512 views 
Graphing Radical Equations using a Table
Problem 5 467 views
Comments (0)
Please Sign in or Sign up to add your comment.
·
Delete