SOLUTION: Use the substitution method to solve the linear system x+y=12 x+3/2y=3/2

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Question 68856: Use the substitution method to solve the linear system
x+y=12
x+3/2y=3/2

Found 2 solutions by checkley71, rmromero:
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
x+y=12
x=12-y now replace x by (12-y) in the other equation thus:
(12-y)+3/2y=3/2
12-y+3/2y=3/2
-y+1.5y=1.5-12
.5y=-10.5
y=-10.5/.5
y=-21 answer.
now substitute 21 for y and solve for x thus:
x-21=12
x=12+21
x=33 answer
proof
33+3/2*-21=3/2
33-63/2=3/2
33-31.5=1.5
1.5=1.5

Answer by rmromero(383) About Me  (Show Source):
You can put this solution on YOUR website!
Here are the Steps using Substition method
1. In either equation, solve for one variable in terms of the other. We are going to solve for y in terms of x.
x+y=12
y = -x+12


2. Substitute -x+12 for y in the other equation x+3/2y=3/2. Solve x.
x%2B%283%2F2%29y=3%2F2 , y = -x+12
x+%2B%283%2F2%29%28-x%2B12%29+=+3%2F2
x+-%283%2F2%29x+%2B+18+=+3%2F2
%28-1%2F2%29x+=+-33%2F2
x = 33


3. Substitute the result from step 2 in either equation. Solve for the other variable y.
x+y=12 , x = 33
33 + y = 12
y = -21


4. Check the solution in both original equations.
x+y=12, x = 33 y = -21
33 +(-21) = 12
33 - 21 = 12
12 = 12 ---------->> True


x%2B%283%2F2%29y=3%2F2, x = 33 y = -21
33+%2B+%283%2F2%29%28-21%29+=+3%2F2
33+-+%2863%2F2%29+=+3%2F2
%2866%2F2%29+-+%2863%2F2%29+=+3%2F2
3%2F2+=+3%2F2 ---------->> True