SOLUTION: 6x+3y=0 8x+5y=8 using either the substitution method or the addition method

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Question 841149: 6x+3y=0 8x+5y=8 using either the substitution method or the addition method
Answer by mxgirl22(39) About Me  (Show Source):
You can put this solution on YOUR website!

Solve using either the substitution method or the addition method.

6x+3y=0
8x+5y=8

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1.) I'm going to label the equations so I can reference back to them.


Equation 1.) 6x%2B3y=0
Equation 2.) 8x%2B5y=8

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2.) I'm going to use the substitution method. Get "y" by itself in equation 1.


Equation 1.)

6x%2B3y=0

6x-6x%2B3y=0-6x

3y=-6x

3y%2F3=-6x%2F3

y=-2x

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3.) Now using y=-2x, plug in to equation 1 or equation 2. Solve for "x".

Equation 2.)
8x%2B5y=8
8x%2B5%28-2x%29=8
8x-10x=8
-2x=8

%28-2x%29%2F-2=8%2F-2
x=-4

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4.) Use either equation 1 or equation 2 and plug in x=-4. Solve for "y".

Equation 2.)
8x%2B5y=8
8%28-4%29%2B5y=8

-32%2B5y=8
-32%2B32%2B5y=8%2B32
5y=40

5y%2F5=40%2F5
y=8

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5.) Check that x=-4 and y=8 for either equation 1 or equation 2.

***Note I'm going to show that both check.

Equation 1.)
6x%2B3y=0
6%28-4%29%2B3%288%29=0
-24%2B24=0
0=0

Checks!

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Equation 2.)
8x%2B5y=8
8%28-4%29%2B5%288%29=8
-32%2B40=8
8=8

Checks!

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6.) Answer.

x=-4
y=8