Question 944587: Can somebody help me solve these equation using substitution ? thanks
1. {3x+4y=-2
{x=6y-8
2. {2x+y=-10
{x=-2y-2
can someone help me please. thank you SHOW all work please!!
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! 1.
3x + 4y =-2
x = 6y - 8
We know that x = (6y-8) so substitute x with this in the 1st equation
3(6y-8) + 4y = -2
distribute
18y - 24 + 4y = -2
Combine like terms
18y + 4y = -2 + 24
22y = 22
divide both sides by 22
y = 1
find x using the 2nd equation; x = 6y - 8; replace y with 1
x = 6(1) - 8
x = 6 - 8
x = -2
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Check your solutions in the 1st equation; 3x + 4y = -2, replace x and y
3(-2) + 4(1) = -2
-6 + 4 = -2, confirms our answers
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2.
2x + y = -10
x = -2y - 2
Substitute (-2y-2) for x in the 1st equation
2(-2y-2) + y = -10
-4y - 4 + y = -10
-4y + y = -10 + 4
-3y = -6
y has to be positive, multiply both sides by -1
3y = 6
divide both sides by 3
y = 6/3
y = 2
find x using the 2nd equation x = -2y - 2, replace y with 2
x = -2(2) - 2
x = -4 - 2
x = -6
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Check this in the 1st equation, replace x & y in 2x + y = -10
2(-6) + 2 = -10
-12 + 2 = -10,confirms our answers
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Was this step-by-step enough? ankor@att.net
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