SOLUTION: I was wondering how would you solve a linear system using subsitution? My teacher taught the class this in like 10 min and I'm not sure.. Can you show me to steps to answer -x+2y=-

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Question 711679: I was wondering how would you solve a linear system using subsitution? My teacher taught the class this in like 10 min and I'm not sure.. Can you show me to steps to answer -x+2y=-6 and 8x+y=31 thanks!
Found 2 solutions by stanbon, lynnlo:
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
-x+2y=-6
8x+ y=31
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You have a choice: solve the 1st equation for "x"
or solve the 2nd equation for "y":
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Solving for x you get:
x = 2y+6
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Substitute for "x" in the 2nd equation and solve for "y":
8(2y+6)+y = 31
16y + 48 + y = 31
17y = -17
y = -1
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Solve for "x" using x = 2y+6
x = 2*-1+6
x = 4
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Cheers,
Stan H.
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Answer by lynnlo(4176) (Show Source):
You can put this solution on YOUR website!
-X+2Y=-6
8X+Y=3
STEP (1)MULTIPLY FIRST EQUATION BY 8
AFTER YOU MULTIPLY YOU WILL HAVE
-8X+16Y=-48
8X+Y=3
STEP (2)ADD THE TWO EQUATIONS TOGETHER TO ELIMINATE X
17Y=-45
STEP(3) FIND Y
Y=-45/17
STEP (4)SUBSTITUTE THE VALUE FOR Y INTO THE ORIGINAL EQUATION TO SOLVE X
-X+2(-45/17)=-6
X=12/17
Y=-45/17