Quick Algebra question?

[imabrat]

I'm doing Multiplying one equation. The first problem is: (as written in the book step by step)

Original Problem
2x + 5y = -22
10x + 3y = 22

This becomes:

5(2x + 5y = -22)
10x + 3y = -22

I don't understand where the 5 comes from. From the different examples in the book, the only explanation I can come up with is if you divide one X by the other. IE 10 divided by 2 is 5. This is the same with the other problem where the Xs are 6 and 2, and I got 3.

Help.

 

[Babyjustrun]

I don't get what you're trying to do.
Are you trying to find the value of x and y?
Because then you should be substituting or doing some sorta weird subtractive thing. If that's what it is, I totally just learned this the other day.

 

[life of the party]

What are you trying to do/ solve for?

 

[imabrat]

I'm solving by elimination.

 

[AliceinHalloweentown]

I think but, I'm not sure, that you need to make the x's similar so you can eliminate them

That way all you'd have left are the y's and the answer to figure out.

Like, you have to subtract them or something... ughh.. math xD

 

[Babyjustrun]

Yes something like that..
You need like, to either cancel them out or make them subtractable?
Jeebus, I just learned this the other day, I kid you not.
I cannot remember.

 

[AliceinHalloweentown]

5(2x + 5y = -22)
10x + 3y = -22

okay so then you've got

10x+25y= -110
10x+3y= 22

25y=-110
3y= 22

22y= -132
y= -6

NOTE: this might be wrong, very, very wrong xD

 

[Padrepride]

I'm doing Multiplying one equation. The first problem is: (as written in the book step by step)

Original Problem
2x + 5y = -22
10x + 3y = 22

This becomes:

5(2x + 5y = -22)
10x + 3y = -22

I don't understand where the 5 comes from. From the different examples in the book, the only explanation I can come up with is if you divide one X by the other. IE 10 divided by 2 is 5. This is the same with the other problem where the Xs are 6 and 2, and I got 3.

Help.

To solve by elimination, you distribute the 5 throughout the top equation. This allows you to eliminate the x by subtracting. Then solve for y. When you get y, plug it into one of the original equations and solve for x. The 5 is just a way to get a common root.

 

[Addicted.to.Speed]

um if your trying to solve for x and y


2x + 5y = -22
10x + 3y = 22

x = 4
y = -6

heres the work


2x + 5y = -22
10x + 3y = 22

times the first equation by -5 than add both equations together

-10x - 25y = 110
10x + 3y = 22
---------------
-22y=132 divide 132 by -22 to get y by itself

y = -6


plug -6 into first equation to solve for x

2x + 5(-6) = -22
2x + -30 = -22

add 30

2x=8

8/2 = 4

x=4 and y=-6

hope that helps

 

[AliceinHalloweentown]

Oh wait.. maybe I was right. XD
I keep editing my messages

 

[::Snow_White::]

We do it the same way Addicted.to.Speed posted.

I don't know why you would times it by positive 5.
But -5, yeah.

 

[Babyjustrun]

Makes perfect sense..
I'll be reviewing this over the weekend for my exam on Wednesday xD

 

[AliceinHalloweentown]

We do it the same way Addicted.to.Speed posted.

I don't know why you would times it by positive 5.
But -5, yeah.

Wait.. yep that makes more sense.. It's official ignore my equation xD I did that anyways though, because I subtracted through.. anywho.

I have H Alg II next year, it should be interesting

 

[PigletGurl]

I'm doing Multiplying one equation. The first problem is: (as written in the book step by step)

Original Problem
2x + 5y = -22
10x + 3y = 22

This becomes:

5(2x + 5y = -22)
10x + 3y = -22

I don't understand where the 5 comes from. From the different examples in the book, the only explanation I can come up with is if you divide one X by the other. IE 10 divided by 2 is 5. This is the same with the other problem where the Xs are 6 and 2, and I got 3.

Help.

You wanna try and solve for one variable. You are multiplying by 5, (which by the way should be -5 so you can eliminate properly), so you can have only one variable in the equation. The common factor of 2 and 10 is 10, so you multiply 2 by 5 to get 10 and negate it. Simple as that.

 

[Addicted.to.Speed]

^^^just wait till you have to solve for x y and z
I hate algebra II

 

[Fatphil32]

Addicted.To.Speed is correct.

 

[::Snow_White::]

Wait.. yep that makes more sense.. It's official ignore my equation xD I did that anyways though, because I subtracted through.. anywho.

I have H Alg II next year, it should be interesting

Ew, I hate algebra.
We did this in Geometry this year too.
It's actually pretty easy once you do it awhile.

I opened this thread and I got all excited because it was the first math question someones asked that I knew.

 

[imabrat]

You wanna try and solve for one variable. You are multiplying by 5, (which by the way should be -5 so you can eliminate properly), so you can have only one variable in the equation. The common factor of 2 and 10 is 10, so you multiply 2 by 5 to get 10 and negate it. Simple as that.

That's what I was asking.
I know how to solve X and Y, but I was just wondering why you multiply by 5 to complete elimination.

Now I got it. Thanks guys!

 

[PigletGurl]

That's what I was asking.
I know how to solve X and Y, but I was just wondering why you multiply by 5 to complete elimination.

Now I got it. Thanks guys!

No prob! I actually enjoy Algebra, mostly II.