Question

How do I know what sign to include when i write the slope-intercept form in inequalities ? For example:
Points given .. (0,5) (3,-1)
Slope= 2
what I got so far..

y=2x+5 <-- how do i know which sign to put there? less than / less than or equal to/ greater than/ greater than or equal to?

Answer 1

(I found slope)

Answer 2

what are you comparing it to?

Answer 3

i guess nothing? It's just asking "Write the slope-intercept inequality for the graph"
on the one i used in example the graph is being shaded from right to left. and the points given are as i gave up there. (0,5) (3,-1)

Answer 4

but im just confused as to what sign to put when i write it in slope intercept

Answer 5

is there an open circle or a closed circle where shading begins/ends?

Answer 6

closed

Answer 7

okay, so if there's a closed circle, then you want to use <= or >=

can you draw the graph?

Answer 8

iill try

Answer 9

k

Answer 10

-.- im having a hard time sry

Answer 11

it's okay. if you need to, just take a screenshot of it and post it here.

Answer 12

i had to change problem sorry, but it's the same thing. uhmm

Answer 13

https://www.desmos.com/calculator

just put y=2x-3

Answer 14

that's what i got in the other problem i told you y=2x-3

Answer 15

points given were (3,3) and (0,-3)

Answer 16

what i got for slope is 2 as well

Answer 17

but what I dont get is if i should put less than/less than or equal to/greater than/greater than or equal to as a sign

Answer 18

:/

Answer 19

no open/closed circle this time?

Answer 20

same, closed circle

Answer 21

i dont think we're that far yet in the lessons, they're all closed dark circles.

Answer 22

solid line though

Answer 23

i know how to figure those out though

Answer 24

try this ..
http://www.freemathhelp.com/systems-inequalities.html

Answer 25

uhm okay

Answer 26

sigh* i'm still having a hard time with this, the thing is i DONT get which side is being shaded, i took this same problems a while ago but it's been months.

Answer 27

what i dont get is, HOW will i know WHICH sign will be used when i write it in slope-intercept form for graphs.

Answer 28

and which side will have to be shaded.

Answer 29

I already know how to figure out slope, and how to write it as a set up to y=mx+b

Answer 30

I closed the question.. thanks to the ones that tried helping though.

Answer 31

If you have y = mx+b for the line already, you'll use y > mx+b if the area *above* the line is shaded (use greater than or equal to if the line is solid, greater than if it's dashed)

y < mx+b if the area *below* the line is shaded (use less than or equal to if the line is solid, less than if it's dashed)

Answer 32

Eg. http://library.thinkquest.org/20991/media/alg2_ineq.gif

http://www.dplot.com/inequality/graphing-inequality-example1c.gif

Answer 33

wow, you put it so simply. one more question if you could help me out with this problem

Answer 34

im given the points (0,5) and (3,-1). it is a dotted line in the graph. and it's being shaded on the left side.

Answer 35

i found the slope is 2

Answer 36

i actually found this site, https://www.desmos.com/calculator and im using it to check if its actually right what i got but it's apparently not

Answer 37

what i got was y<2x+5.. but it's wrong..? :I i got a test tomorrow..

Answer 38

I just rechecked.. uhm, i got y<-3x+5..

Answer 39

whaa no im confusing myself ._.

Answer 40

The slope isn't 2...m = (-1 - 5)/(3-0)

Answer 41

-2x+5* ._.?

Answer 42

oh, i used 0,5 as x sub 2 y sub 2

Answer 43

so.. uhm, y<-2x+5?

Answer 44

That looks correct but this would be far easier with seeing the graph.

Answer 45

yeah sorry.. but ! enter what i just gave you into the calculator which is this:
https://www.desmos.com/calculator

Answer 46

i just found it half hr ago, it is quite useful.

Answer 47

it is if i my judgement is correct exactly as the one on the problem

Answer 48

did you disappear? lol

Answer 49

anyway i think things are starting to sink in and im starting to remember how to do them from before.

Answer 50

from what you told me

Answer 51

I gotta go to sleep, good luck on your test!

Answer 52

okay, have a good one, and thank you! =)