SOLUTION: {{{x+3y=6}}} {{{x-3y=12}}}

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Question 28862: x%2B3y=6
x-3y=12
Answer by sdmmadam@yahoo.com(530) About Me  (Show Source):
You can put this solution on YOUR website!
x+3y=6 ----(1)
x-3y=12 ----(2)
We observe that if we add the two equations,since the coefficients of y are eqaul in magnitude and opposite in sign,the y-variable gets eliminated.
(1) +(2) implies
(x+x)+(3y-3y) = (6+12)
2x+0 =18
2x=18
x=18/2 = 9
Putting x=9 in (1)
x+3y = 6
9+3y =6
3y = 6-9
3y = -3
y = -3/3 =-1
Answer: x=9 and y = -1
Verification: checking x=9 and y = -1 in (2)
LHS = x-3y = 9- 3X(-1) = 9+3 = 12 = RHS
Therefore our values are correct