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New Member
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Feb 7, 2008, 05:51 PM
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9th grade algebra: elimination
Im in 9th algebra && I need help with elimination..
Does anyone know how to do this?
Thanks
:)
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Ultra Member
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Feb 7, 2008, 05:54 PM
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No, no one knows how. Can you please explain?
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Jobs & Parenting Expert
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Feb 7, 2008, 05:58 PM
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Yes. It's lots of fun--one of the funnest things in algebra. Elimination by addition and subtraction or by multiplication?
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Jobs & Parenting Expert
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Feb 7, 2008, 05:59 PM
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New Member
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Feb 7, 2008, 06:01 PM
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its elimination by addition && subtraction.
the problem I need help with is:
3x+4=19
3x+6y=33
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Jobs & Parenting Expert
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Feb 7, 2008, 06:03 PM
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Originally Posted by vannaboo
its elimination by addition && subtraction.
the problem i need help with is:
3x+4=19
3x+6y=33
Are you sure you copied that correctly?
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New Member
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Feb 7, 2008, 06:18 PM
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Hahaha
Sorry.
I left out the y by the 4
:)
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New Member
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Feb 9, 2008, 10:24 AM
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Just imagine that any equation is like a balance
x- box with some not known own weight
y- basket with some not known weight
So you are sure that 3 boxes and 4 baskets are exactly 19 kg weight
And you know that 3 boxes and 6 baskets are giving 33 kg
Imagine now
You can take out from the balance same weight from the left and from the right side, the balance will still stay in equilibrium
And do it
Take from the left side of the second balance 3 boxes and 4 baskets, and take from the right 19 kg
What is remaining?
2 baskets on left equal to 14 kg
It is logical any basket is exactly 7 kg…….
And ooooops do we have a problem?
4 baskets are 28 kg?
What about the boxes?
They are obviously foul with Helium, like balloons, they are not pushing the left side of the equations down, they are lifting, just like any quantity with negative sign.
Any basket is lifting with force equal to?
3*x+4*7=19
3*x=19-28
3*x=-9
X=-3
Each box is lifting with force equal by intensity to 3kg, but because this is lifting force the sign is –
Think
You can find similar illustrations for any system.
You can work with prices instead of weights….
All the best
And more work
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Ultra Member
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Feb 9, 2008, 09:37 PM
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3x + 4 = 19
Subtract 4 from both sides The 3x would stay
The 4 disapears
19 - 4 = 15
Now you have 3x = 15 All you have to do now is to divide both sides by 3
Answer: x = 5 That one is easy
If x is the same in both problems,
3x + 6y = 33 becomes 15 + 6y = 33
To solve that one, subtract 15 from both sides 15 - 15 =0
33 - 15 = 18
The new equation is 6y = 18 What is y? It is 3.
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New Member
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Feb 12, 2008, 06:32 PM
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For the following set of numbers, find the average. The median, and the mode. 22,16,23,17,25,25?
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Uber Member
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Feb 12, 2008, 08:24 PM
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Originally Posted by saoco
for the following set of numbers, find the average. the median, and the mode. 22,16,23,17,25,25?
It would be good to start your own thread with this, especially since no one expects to find this under a thread entitled "elimination."
Do you remember learning how to do an average clear back in elementary school? Same thing. Only usually we call it a "mean" in statistics.
To get the medium, you will need to "order" the numbers, that is, put them from smallest to largest. Then find the middle. If you have an odd number of elements, it's literally the middle. (i.e. if you have 7 items then it's the 4th one over, the middle one.) If it's an even number, like you have, it's the average of the two center ones. (i.e. the average of the 3rd and 4th one.) That'll be easier to see once you have them ordered.
A mode is which thing appears most often in the set.
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New Member
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Apr 10, 2010, 09:05 PM
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I assume you mean 3x+4y=19 so
3x+4y=19
3x+6y=33
subtract the equations
0x-2y=-14
divide -14 by 2
y=-7
put -7 in for y in one of the equations
3x+4(-7)=19
3x-28=19
add 28 to both sides
3x=47
take 47/3
x=15.6666
(15and2/3,-7)
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New Member
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Apr 10, 2010, 09:08 PM
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sorry I meant y=7 not -7
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