Posted by **xxx** on Sunday, May 3, 2009 at 5:45am.

I need to graph "y = -2x+5" and "y = 4/5x-3"...

I don't think it's possible to help graphing on this site.. so can you please tell me any other sites where it would show how to graph those equations?

also, I'm having trouble graphing INEQUALITIES. any help on that??

thanks a lot :)

any help is appreciated.. thanks :)

- math (graphing) -
**Reiny**, Sunday, May 3, 2009 at 8:39am
here is an easy way to draw a graph of a straight line if you given the equation in the form y=mx+b

remember that m is the slope and b is the y-intercept and slope = rise/run

then for y = (4/5)x - 3, rise/run = 4/5

and the y-intercept is -3

1. plot the y-intercept (0,-3)

2. from there count 5 units to the right, then 4 units up, basically doing a run of 5 and a rise of 4.

join the two points, and you are done.

for the first one:

y = -2x + 5 or y = (-2,1)x + 5

plot (0,5), and from there count 1 unit to the right and then 2 units **down**, join the points ...

All done

- small typo -- math (graphing) -
**Reiny**, Sunday, May 3, 2009 at 8:41am
near the end

<<y = -2x + 5 or y = (-2,1)x + 5 >>

should read:

y = -2x + 5 or y = (-2/1)x + 5

- math (graphing) -
**xxx**, Sunday, May 3, 2009 at 1:36pm
Thank you VERY much! You're my savior :)

just one more question.. I NOW understood how to graph equations.. but I still have to graph inequalities, which seems much more complicated from my point of view.

I've got two inequalities that I have to graph.

1. y > 2/3x-4

2. y < -2

NOTE: Number 1, where it says "y > 2/3x-4"... well under ">" there is a line/dash, as to mean that it's "greater than or equal to". I hope you understand what I mean..

thanks for your help.. :)

- math (graphing) -
**Reiny**, Sunday, May 3, 2009 at 1:49pm
y ≥ (2/3)x-4

graph y = (2/3)x - 4, then shade in the region ABOVE that line

had it been

y > (2/3)x-4 the boundary is the line

y = (2/3)x - 4, so draw a dotted line instead of a solid line

in general if y > mx + b

draw a dotted line for y = mx + b and shade in the region above the line

if y < mx + b

draw a dotted line for y = mx + b and then shade in the region BELOW the line

- math (graphing) -
**xxx**, Sunday, May 3, 2009 at 2:08pm
okayyy..

what about "y < -2" ????

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