SOLUTION: 2. Solve for X and Y in the following problems. Make sure you show all your work so you can get partial credit even if your final answer is wrong. a. X + Y= 10 , 3X + Y = 12

Algebra ->  Linear-equations -> SOLUTION: 2. Solve for X and Y in the following problems. Make sure you show all your work so you can get partial credit even if your final answer is wrong. a. X + Y= 10 , 3X + Y = 12      Log On


   

Question 305703: 2. Solve for X and Y in the following problems. Make sure you show all your work so you can get partial credit even if your final answer is wrong.
a. X + Y= 10 , 3X + Y = 12
b. 2X + 5Y = 19 , 3X + 3Y = 15
c. 4X + Y = 22 , 2X + 3Y = 16
d. 12X + Y = 174 , 8X - 2Y = 36
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
I'll do the first one to show you the general procedure.
Then I'll give you the final answers for the rest but work through the problems to show all the work.
Re-post if you get stuck or don't get the final answer.
a)
1.X+%2B+Y=+10
2.3X+%2B+Y+=+12
Use one equation to get X as a function of Y and then substitute in the other equation.
1.X%2BY=10
X=10-Y
Now substitute into eq. 2,
2.3X%2BY=12
3%2810-Y%29%2BY=12
30-3Y%2BY=12
-2Y=-18
highlight%28Y=9%29
Now use either equation to find X.
X=10-Y
X=10-9
highlight%28X=1%29
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It doesn't matter if you find Y as a function of X or vice versa.
It doesn't matter if you start with the second equation and substitute into the first.
You'll get the same answer.
Sometimes you can avoid fractions and make the job easier but you'll get the same answer (or you should get the same answer).
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b. +X=2+ , Y=3
c. X=5 , Y=2
d. X=12 , Y=30