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Mathematics 8 Online
OpenStudy (anonymous):

How exactly do you know when you need to change a inequality into y=mx+b?

OpenStudy (anonymous):

@Loser66

OpenStudy (anonymous):

Should I always do it ?

OpenStudy (amistre64):

the form is irrelevant to the math of it.

OpenStudy (anonymous):

But when graphing it makes a difference

OpenStudy (loser66):

it relates to the previous one

OpenStudy (amistre64):

no, its only in the eye of the beholder

OpenStudy (anonymous):

wtf...

OpenStudy (amistre64):

so a 2 parter eh

OpenStudy (loser66):

To me, ALWAYS

OpenStudy (anonymous):

Which inequality will have a shaded area below the boundary line? y – x > 5 2x – 3y 3 2x – 3y 7x + 2y 2 3x + 4y > 12

OpenStudy (anonymous):

So I should change them all to y=mx+b before considering them?

OpenStudy (loser66):

Now, BELOW, right?

OpenStudy (anonymous):

Right

OpenStudy (amistre64):

not =, but the proper symbol. butill let yall finish up where yall left off

OpenStudy (loser66):

hence, you need y < (lesser) no need to change, just consider which inequality has y < something

OpenStudy (anonymous):

Well I have to put them into that form to see which is y<

OpenStudy (loser66):

hahaha, you missed a bunch of symbols from b,c,d

OpenStudy (loser66):

Type the problem carefully, PLEASE

OpenStudy (anonymous):

OpenStudy (loser66):

you CAN do it

OpenStudy (anonymous):

Give me a second

OpenStudy (anonymous):

D?(:

OpenStudy (loser66):

yup

OpenStudy (anonymous):

I'm going to make it into that form for every problem.. That couldn't hurt huh?

OpenStudy (loser66):

yes

OpenStudy (amistre64):

as long as you remember to flip the symbol when needed

OpenStudy (loser66):

it is easy to do, just practice more

OpenStudy (anonymous):

Gotcha! Thanks a million, good teacher

OpenStudy (anonymous):

@amistre64 When I graph something such as 3x + 4y > 12 it changes the look of the graph when I put it into the other form...

OpenStudy (amistre64):

3x + 4y > 12 let x=0 to investigate how this moves along the y axis 4y > 12 y > 3 the true region is therefore is all the points above 3

OpenStudy (amistre64):

7x + 2y <= 2, see how this moves along the y axis, let x=0 2y <= 2 y <= 1 , all the points under y=1 are true, so the shade is under the line

OpenStudy (amistre64):

notice that i dont even have to graph them ... i just observe the movement along the y axis

OpenStudy (anonymous):

Yeah I see that

OpenStudy (anonymous):

Am I missing something.. The top and bottom answer are the same??

OpenStudy (amistre64):

an aside ... the intercept form of a line, if you ever want to just graph the intercepts \[ax+by=c\] \[\frac{ax}{c}+\frac{by}{c}=\frac cc\] \[\frac{x}{c/a}+\frac{y}{c/b}=1\] when x=0, y=c/b when y=0, x=c/a

OpenStudy (amistre64):

the top and bottom graphs do appear to be alike yes

OpenStudy (anonymous):

wtf.. They're both the right answer too

OpenStudy (anonymous):

Which graph represents the solution set for the system x + 2y 3, x + y 4, and 3x − 2y 4?

OpenStudy (amistre64):

ive had some computer programed stuff like that ... it trying to pull a random set whats the actual question?

OpenStudy (anonymous):

thats the question

OpenStudy (amistre64):

its missing the <> stuff

OpenStudy (anonymous):

lol one second

OpenStudy (anonymous):

OpenStudy (amistre64):

x + 2y <= 3 ; 3,0 and 0,1.5 2y <= 3 y <= 1.5 we have a shade under the blue line x + y >= 4 ; 4,0 and 0,4 y >= 4 we have a shade above the red line 3x - 2y >= 4 ; 4/3, 0 and 0,-2 for variety, lets do y=0 3x >= 4 x >= 4/3, its shaded to the right of the green line

OpenStudy (amistre64):

|dw:1430878057505:dw|

OpenStudy (anonymous):

WTTTFFFF... How did I not do it right

OpenStudy (amistre64):

please curb the profanity ...

OpenStudy (anonymous):

What the fudge..

OpenStudy (amistre64):

we can always dbl chk the point 4,1 x + 2y <= 3 4 1 4 + 2 = 6 <= 3 is false <---- it doenst work here x + y >= 4 4 1 4 + 1 = 5 >=4 is true 3x - 2y >= 4 4 1 12 - 2 = 10 >= 4 is true

OpenStudy (amistre64):

lol, thats better ... wtf has a specific and profane meaning.

OpenStudy (anonymous):

I wish I could show you how I got the answer but It's on a graph

OpenStudy (amistre64):

i defined the shaded region by observing the movement along an axis ... then i was able to detemrine which line was which by the intercepts alone; and then i simply applied the shading in the direction

OpenStudy (anonymous):

Here let me try to show you what I tried to do and see if you can see why its wrong

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