## need help graphing and finding points

Simple patterns, variables, the order of operations, simplification, evaluation, linear equations and graphs, etc.
bbb95
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Joined: Wed May 13, 2009 2:04 am
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### need help graphing and finding points

trying to figure out graphing on -4(2x+y)=or grater than -8

Martingale
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### Re: need help graphing and finding points

bbb95 wrote:trying to figure out graphing on -4(2x+y)=or grater than -8

Are you wanting to graph $-4(2x+y)\geq-8$

try looking at
Graphing Linear Inequalities

sdbielz
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Joined: Sun Jul 19, 2009 4:53 pm
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### Re: need help graphing and finding points

-4(2x+y)=or grater than -8 [distribute]

-8x-4y =or> -8 [isolate the y]

-4y=-8+8x [divide both sides by the -4, and don't forget to flip the inequality sign bc you divided by a negative number]

y <= 2-4x

now just find the intercepts; at which point does x=0, and y=0

(0,2) (1/2,0)

next, we find the slope, which is simply the change in Y over the change in X. (Y-y/X-x)

(2-0)/(0-.5)====2/-.5

we simplify this by 'unreducing'....ironically. 4/-1.

so the slope is negative (drops from left to right) and raises 4 units for every 1 unit it shifts left.

I would use this concept to plug in see if y<=-2 when x is 1.... kinda to check my work. and it appears to be correct.

now you have three points to plot... (0,2) (.5/0) and (1,-2).

Draw a SOLID (bc its <=) line through the points, and shade in everything below it...bc its less than or equal to.

hope this helped...