SOLUTION: how do I go about solving these linear equations using substitution 4x-y=5 4x+4y=-4 I know I have to add to both sides of the first one but I do not remember which sides or whe

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: how do I go about solving these linear equations using substitution 4x-y=5 4x+4y=-4 I know I have to add to both sides of the first one but I do not remember which sides or whe      Log On


   



Question 950397: how do I go about solving these linear equations using substitution
4x-y=5
4x+4y=-4
I know I have to add to both sides of the first one but I do not remember which sides or where to go from there.

Found 2 solutions by Alan3354, stanbon:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
how do I go about solving these linear equations using substitution
4x-y=5 --> y = 4x-5
4x+4y=-4
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Sub for y in the 2nd eqn
4x + 4(4x-5) = -4
x + 4x-5 = -1
5x = 4
x = 4/5
------
y = -9/5

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
go about solving these linear equations using substitution
4x-y=5
4x+4y=-4
----
Modify::
y = 4x-5
x + y = -1
-------------------
Substitute for "y" and solve for "x"::
x + 4x-5 = -1
----
5x = 4
x = 4/5
----
Solve for "y"
x + y = -1
4/5 + y = -1
y = -9/5
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Cheers,
Stan H.
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