solve equation by graphing y=-x-8 9x-8y=-21 please someone help me step by step so i can learn to do this on my own

- anonymous

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- amistre64

do you have graph paper?

- anonymous

yes

- amistre64

then establish a horizontal line and call it X; draw a vertical line and call it Y

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## More answers

- anonymous

did that

- amistre64

where the 2 lines cross, call it (0,0) and we can then plot other points from that origin.

- amistre64

get 2 different colored crayons , one for each line that we are going to plot...

- anonymous

i have numbered graph paper

- anonymous

k

- amistre64

numbered what???....... thats just cheating ;)
y=-x-8 since this is an equation for a line, we only need 2 points to draw a line with right?

- anonymous

what, no my graph paper is pre-numbered y,x 10,-10

- amistre64

back in my day we had to work to get numbers on graph paper lol

- anonymous

yeah i was doing that way till i found it online and printed a bunch

- amistre64

online???...... oh well :)
So lets plot 2 points for this y=-x-8 equation. What are your 2 favorite numbers for an x ?

- anonymous

any #'s?

- amistre64

any number between -10 and 10 would be helpful :)

- anonymous

5, -3

- anonymous

he easy form is must include :
-name of a drug
-history of drug
-street name
-short +long term effect
-how is it ingested
-what effects does it have on body
-anyother intersting facts
amisstro plz help me write an essay

- amistre64

ok...les start with ....... -3.
when x = -3 our equation becomes:
y=-x-8
y=-(-3)-8
y = 3-8
y = -5

- amistre64

i dont do essays very well...srry

- amistre64

with this bounty of knowledge we have just obtained we can use it to make a point on the graph.

- amistre64

put your crayon on the x = -3 part of the X axis

- anonymous

Is Mary still there?

- anonymous

(-3,-5)

- anonymous

yeah

- anonymous

Okay, The drug Lisinopril is used for high blood pressure.

- amistre64

yes, we put a point at (-3,-5)

- amistre64

if yall can take this discussion to another post, that would be helpful :)

- anonymous

yes please

- anonymous

sure

- anonymous

write it in paragraphas

- amistre64

Now we can use x = 5 and see what we get.
y=-x-8
y=-(5)-8
y = -13 (5,-13) gonna have to get longer graph paper for that one ;)

- anonymous

can we go to the english section and help me i posted there

- anonymous

graphed

- amistre64

now we use the other equation, in a different color, and graph its line..

- anonymous

can we go to the english section and help me i posted there

- amistre64

9x-8y=-21 , the easiest numbers to use are 0 right?

- anonymous

right

- amistre64

ok lets use x = 0 and find a value for y.
9(0)-8y=-21
-8y = -21
y = 21/8 (0,21/8)

- amistre64

21/8 = 2' 5/8

- anonymous

amistre64
the essay form is must include :
-name of a drug
-history of drug
-street name
-short +long term effect
-how is it ingested
-what effects does it have on body
-anyother intersting facts

- amistre64

when y = 0 x = what?
9x-8(0)=-21
9x = -21
x = -21/9 (-21/9 , 0)
-21/9 = -2' 3/9 = -2' 1/3

- anonymous

can we go to the english section and help me i posted there

- amistre64

mary: I dont write essays :) please take it to another post.

- anonymous

hold on i got lost, im really bad at math

- amistre64

tell me where we got lost :)

- anonymous

21/8=2 5/8

- anonymous

what would my point be for that

- amistre64

(x=0, y= 2' 5/8) that 'mark helps to define the integer from the fraction

- amistre64

go up 2 and then mark just a liitle above halfway

- anonymous

so to graph it (0,2'5/8)

- amistre64

that would pe one point on the graph of a new line equation.... different colors right?

- anonymous

right

- amistre64

the second point is on the x aixs because we made y = 0 right?

- amistre64

(-2' 1/3 , 0) is our other point, not connect these points with a line

- amistre64

not means now.... typos persist

- anonymous

on my paper it asks what is the solution of the equation x=? y=?

- anonymous

sry solution of the system of equations

- amistre64

where the lines that we graph cross, where they meet up is a single point. It is asking for the point where the 2 lines meet.

- anonymous

by my graphing they dont

- amistre64

we started by finding 2 points for the line to travel thru, but the ends never quit, they go on and on and on.... these lines meet at one point, and that point is our solution.
Did you extend your lines until they meet at that point? or did you just connect from dot to dot?

- anonymous

wait i didnt draw the lines all the way thru

- anonymous

is it (-5,-2)

- anonymous

(-5,-3)

- amistre64

Dunno, you graphed it ;) but lets put those numbers in our equations and see how good they are...
y=-x-8
-2 = --5-8
-2 = 5-8
-2 = -3 ..... its a false statment, but we know its close :)
9x-8y=-21
9(-5)-8(-2)=-21
-45 + 16 = -21
-29 = -21 .... wanna try that -3 instead?

- anonymous

need a ruler, using a folded piece of paper

- amistre64

the solution by graphing is just a technique, after you use it to "see" what is going on for a solution, you will never really use it again unless you need a visual.

- anonymous

how often are u on here i need a ft tutor

- amistre64

as long as the library is open and I dont have class :) ....alot ;)

- anonymous

ok well i go to strayer university i am always on line, and like i said i really really suck at this kind of math so i always need help
got to go for now but will be back on later up until about 3am nc time

- amistre64

nc ...im in florida :) might be here between 9 and 2

- anonymous

morning i assume?

- anonymous

same time zone,

- amistre64

yep, same zone, college library closes at 2am... I should be around here somewhere. Im the guy with all the fans lol

- anonymous

yes u r we could exchange numbers if you want that way hearing it sometimes makes better sense

- amistre64

id rather keep it online ;) you can emailme at tony031172@gmail.com if you need to get in touch with me.

- anonymous

ok great aatinabo@yahoo

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