SOLUTION: I have a few math questions that I need help with. Can you show me how to do these problems?? 2y-3x=4 2y-5x=8 y= -3x+7, y= -2x- 5 x+y = 8, x-y = 12

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Question 302120: I have a few math questions that I need help with. Can you show me how to do these problems??
2y-3x=4
2y-5x=8
y= -3x+7, y= -2x- 5
x+y = 8, x-y = 12
Found 2 solutions by richwmiller, stanbon:
Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website!
some website rules
One problem at a time.
No similar problems
limit 4 problems daily
Plus you didn't say what you are trying to do with the equations.

Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
2y-3x=4
2y-5x=8
Solving by elimination.
Subtract the 2nd equation from the 1st to get:
2x = -4
x = -2
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Substitute into either of the original equations and solve for "y":
2y -3(-2) = 4
2y + 6 = 4
2y = -2
y = -1
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Solution: (-2,-1)
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y= -3x+7,
y= -2x- 5
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Solve by substitution:
-3x+7 = -2x-5
Add 3x to both sides to get:
x-5 = 7
Add 5 to both sides to get:
x = 12
---
Substitute into either of the original equations and solve for "y":
y = -3(12) + 7
y = -36 + 7
y = -29
---
Solution: (12,-29)
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x+y = 8
x-y = 12
---
Solve by elimination:
Add the two equations to get:
2x = 20
x = 10
---
Substitute and solve for "y":
10+y = 8
y = -2
---
Solution: (10,-2)
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Cheers,
Stan H.