y = 8x − 9
y = 4x − 1
Part A: Explain how you will solve the pair of equations by substitution or elimination. Show all the steps and write the solution.
Part B: If the two equations are graphed, at what point will the lines representing the two equations intersect? Explain your answer.

- anonymous

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- anonymous

what is a variable that u can eliminate?

- anonymous

X? I think. I'm completely lost

- anonymous

treat this as an equation

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## More answers

- anonymous

You can add or subtract to eliminate a letter (x or y).

- anonymous

\[\frac{ y=8x-9 } { y=4x-1 }\]

- anonymous

so can you see any thing that can be eliminated by subtraction or addition?

- anonymous

hello??

- anonymous

9-1??? Sorry I didn't reply I got sidetracked

- anonymous

do u know wit a variable is?

- anonymous

@andrea0529

- anonymous

I'm sorry I really need help I suck at math pls

- UsukiDoll

For part B, we graph these two equations y=8x-9 and y= 4x-1
then the point of intersection is when there is a solution for both of these equations

- UsukiDoll

For part A. substitution is a better choice.

- anonymous

u can eliminate y

- anonymous

so it becomes \[\frac{ 8x-9 }{ 4x-1 }\]

- anonymous

Why would you say that I came on here for help because I care about my education not to be insulted by rude people like you.

- UsukiDoll

and how the heck can you solve with that?

- UsukiDoll

anyway set these two equations together
8x-9 = 4x-1
put all variables to the left and all numbers to the right
8x-4x=-1+9
now what's 8x-4x and what's -1+9 ?

- anonymous

Fine I don't want your help. You didn't hack me shut up.

- UsukiDoll

-_- ughhhh @ganeshie8

- UsukiDoll

@Icedragon50 stop creating drama on here. Just leave if you can't help nicely to other OS users.

- anonymous

Thank you @usukidoll for actually helping me

- anonymous

\[8x-y=9\]\[4x-y=1\]

- anonymous

looking it this way might help

- UsukiDoll

@saseal that works too
elimination or substitution can give the same results.

- anonymous

-1+9=8 thanks so much

- UsukiDoll

forgot one part though
8x-4x=-1+9
now what's 8x-4x and what's -1+9 ?
what's 8x-4x ?

- anonymous

yea its easier to put in matrix form that way :)

- UsukiDoll

true, but most of the time , matrix form versions are taught way later o_O.

- UsukiDoll

@andrea0529 what's 8x-4x ?
or an easier way to put it by factoring the x
x(8-4) what's 8-4 ?

- anonymous

4x

- anonymous

yea, once you go matrix you dont go back!

- UsukiDoll

:)
so now we have 4x = 8
we divide 4 from both sides
so what's 8/4 ?

- UsukiDoll

8 divided by 4 @andrea0529
then we have x by itself after that step.

- UsukiDoll

|dw:1438679720781:dw|

- anonymous

8/4=2 so x=2

- UsukiDoll

yes so now that we have x = 2 , we can plug it into one of the equations to solve for y
let's pick the second equation
y=4x-1
so we plug in x = 2 into y = 4x-1
y=4(2)-1
y=8-1 = ?
what's 8-1 ?

- anonymous

8-1=7

- UsukiDoll

mhm so x = 2 and y = 7
we can plug these numbers back to the equation to see if they hold true. That means we have done this correctly

- UsukiDoll

7=4(2)-1
7=8-1
7=7
7=8(2)-9
7=16-9
7=7

- UsukiDoll

so we have done this correctly. Apparently at the point (2,7) the two lines should intersect

- UsukiDoll

but it's asking for a graph so we need to make tables... -_-
we can let x = 0,1,2 to solve for y for y = 8x-9 and y = 4x-1

- UsukiDoll

|dw:1438680048402:dw|
so for this chart we plug in x= 0 for those 2 equations... similarly plug in x = 1 for those two equations as well until we hit the x = 2 which results in 7 for both equations

- UsukiDoll

|dw:1438680137485:dw|
so can you plug x = 0 for
y = 8x-9
y=4x-1
and
can you plug x = 1 for
y=8x-9
y=4x-1
???
since x = 2 is done already, I've wrote y = 7 on both of them.

- anonymous

##### 1 Attachment

- UsukiDoll

yeah what this guy wrote ^

- UsukiDoll

because graphing manually is a pain. I think I overshot part b. oh well .

- UsukiDoll

but (2,7) is a point that two lines cross (point of intersection)
and there is one solution when we have perpendicular lines.

- UsukiDoll

@andrea0529 overshot part b. it was just asking the point of intersection with is (2,7) .

- anonymous

Okay I get it know I mostly needed help with part a. I've got part b. Thank you so much.☺️

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