Question

Can someone please help me understand domains and ranges in context to graphing?! I'm so confused

Answer 1

Domains are the x's and the ranges are the y's.

Answer 2

Ok so, then, how do you find what they are in a problem?

Answer 3

Like....What do you mean?? Explain. What kind of problem?

Answer 4

If it would be this: (2,5) 2= domain 5= range

Answer 5

Basically, the domain is the set of x's that doesn't break the equation. Some common things that "break" equations:

Dividing by 0
Square root of negative numbers
Logarithms of negative numbers

Answer 6

I mean, like find the domain and range of this function kind of problems

Answer 7

So, if you have:
\[y=\frac{ \sqrt{x+5} }{ 3-x }\]
It won't work when x+5<0, or when 3-x=0

So, the domain is all x≥-5, except for x=3

Answer 8

Umm, what? Iso you change the 5 to a negative?

Answer 9

so*

Answer 10

For square root, the domain is where the function under the square root is greater than or equal to 0. If it were less than 0, the function would not work.

So, we have to solve:
x+5 ≥ 0 → x ≥ -5

Answer 11

but I thought that we weren't supposed to use negatives? and why is equal to used instead of equals?

Answer 12

It's not that x can't be negative, its that the function under the square root can't be negative.

Answer 13

Ok, so i think I get that, but I am still completely lost when it comes to graphing square root functions

Answer 14

When you graph a square root function, you start at the x point when the function under the square root sign equals zero, then plot a few points from there.

Answer 15

Ok thank you so much for trying to explain it to me lol I really appreciate it

Answer 16

Yup, sorry if I didn't explain it very well.

Answer 17

you did great