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#1 2014-07-28 04:03:40
- Gabrielle
- Guest
Solving Systems of Equations Using Substitution Method and Elimination
Ive done these multiple times and I feel like giving up. I don't understand what my teacher is saying.
#8
y=(1/2)x-3
y=(3/2)x-1
y=(1/2x-3
(3/2)x-1=(1/2)x-3
+1 +1
(3/2)x=(1/2)x-2
(4/2)x= -2
4x = -2
x= -2
y=(3/2)x-1
y=(3/2)-2-1
y=-3-1
y= -4
(-2,-4)
#12
4x + 3y= -15
y=x+2
4x+3(x+2)=-15
4x+3x+6=-15
7x=-21
x=-3
y=x+2
y=-3+2
y=-1
(-3,-1)
#16
y=-2x+1
y=x-5
y=3x+6
x=2
y-6=3x
y=-3x
(2,-3)
and this is what my teacher said...
#8 - Tell me what you did to get from the first step to the second.
(3/2)x=(1/2)x-2
(4/2)x= -2
#12 - The work must show elimination. You have used substitution. Try again.
#16 - I don't see your elimination work. Please look at the example that I provided in my last post to help you show your work for #12 and #16.
she gave me this example but im not sure how to put my problems like this
Your work doesn't flow very well. You do not need to fix this one, but take a look at the proper way to show your work.
x + 2y = -4 Already in standard form.
4y = 3x + 12 Write in standard form.
--------
x + 2y = -4
-3x + 4y = 12 Now determine what you need to multiply the equations by.
--------
3(x + 2y = -4)
3x + 6y = -12
-3x + 4y = 12 Now add the equations together to eliminate the x's.
------------------
10y = 0
y = 0 Substitute 0 for y in one of the original equations.
-----------------
x + 2y = -4
x + 2(0) = -4
x = -4
(-4, 0)
#2 2014-07-28 04:05:39
Re: Solving Systems of Equations Using Substitution Method and Elimination
Hi;
What sort of help can We provide you?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#3 2014-07-28 04:09:22
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Solving Systems of Equations Using Substitution Method and Elimination
Hi;
The question has already been answered by bob bundy.
http://www.mathisfunforum.com/viewtopic … 82#p326582
Please go there.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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