#1

My teacher has given us a big graph and told us to make a picture on it but it has to include several types of lines (parallel, perpendicular, etc) and two absolute value graphs. So i've drawn a house and fulfilled all the requirements but the second part is to write the equations and domain restrictions of the lines. Would an equation really only be necessary for a slanted line or absolute value graphs? Do the domain restrictions just basically say to what points a certain line extends as to not imply that the lines go on forever? How do you write the domain of a line?

#2

Equations for absolute value are needed. That's all I know, sorry.

#3

#4

*Do the domain restrictions just basically say to what points a certain line extends as to not imply that the lines go on forever?*

yep

*How do you write the domain of a line?*

in school here we did it like: x ∈ [-2,2]

and everything is some kind of equation so I don't get what you're getting at

#5

we did that in 6th grade

#6

masamune im pretty sure thats not what i'm looking for

#7

say you got a line going from (2,3) to (6,7)

the eq should be something like

y=x+1

and domain restriction is X is greater than or equal to 2 and less than or eqaul to 6.

use symbols ofcourse.

the eq should be something like

y=x+1

and domain restriction is X is greater than or equal to 2 and less than or eqaul to 6.

use symbols ofcourse.

#8

The domain is the set of x values for which the curve/line works. So for a straight line extending forever, that's "All real x" because it is true for all values of x. If the line only lies between x=2 and x=5, then the domain would be 2 <= x <= 5

The range, if this is important, is the same, but for function/y values. The range of an absolute value graph sitting on y=0 would be y >= 0.

edit: in case you didnt know, they arent arrows. They are "Less than or equal to" and so forth.

The range, if this is important, is the same, but for function/y values. The range of an absolute value graph sitting on y=0 would be y >= 0.

edit: in case you didnt know, they arent arrows. They are "Less than or equal to" and so forth.

*Last edited by syk3d at Oct 9, 2008,*

#9

If you're doing it on a graphing calculator:

1. Vertical lines aren't possible on a graphing calculator's y= feature due to the fact that it interprets them as functions of x, and a vertical line fails the vertical line test for a function.

2. Domain restrictions look like this:

y = blah blah blah | 3<x<6

on a calculator.

1. Vertical lines aren't possible on a graphing calculator's y= feature due to the fact that it interprets them as functions of x, and a vertical line fails the vertical line test for a function.

2. Domain restrictions look like this:

y = blah blah blah | 3<x<6

on a calculator.

#10

If you're doing it on a graphing calculator:

1. Vertical lines aren't possible on a graphing calculator's y= feature due to the fact that it interprets them as functions of x, and a vertical line fails the vertical line test for a function.

2. Domain restrictions look like this:

y = blah blah blah | 3<x<6

on a calculator.

get a calculator that does parametric plots?

#11

ah ok, i found some old notes and i'm all good with how to get the domain and stuff now, thanks =)

#12

one more thing actually, when graphing a line... say i have I have a vertical line on (3,0) and it goes up and down 4 units so the domain would be -4<y<4 right? but do i have to put x=3 as well? so the complete domain would be like x=3 -4<y<4 or something?

#13

one more thing actually, when graphing a line... say i have I have a vertical line on (3,0) and it goes up and down 4 units so the domain would be -4<y<4 right? but do i have to put x=3 as well? so the complete domain would be like x=3 -4<y<4 or something?

If the line spans 4 units, then no. You'd put:

__ < y < __

First blank is the lowest value for y that the line starts at, and the second blank is the highest.

So if I had a vertical line from -2 to 11, I would write:

-2 < y < 11

To show that y will always be greater than -2 (or -2 is not greater than y) and that y will always be less than 11