SOLUTION: x+y=9 and y=2x

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Question 596080: x+y=9 and y=2x
Answer by math-vortex(648) About Me  (Show Source):
You can put this solution on YOUR website!
Hi, there--
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We can use the the substitution method to solve this system.
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x%2By=9
y=2x
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Since y is equal to 2x, we can substitute 2x for y in the first equation, and solve for x.
x%2By=9
x%2B2x=9
3x=9
x=3
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Now substitute 3 for x into either equation and solve for y. I'll use the second one.
y=2x
y=2%283%29
y=6
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According to our algebra the ordered pair (3,6) in the solution for this system.
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It's ALWAYS a good idea to check this solution in the original equations to make sure we did not make a mistake.
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CHECK:
x%2By=9
%283%29%2B%286%29=9
9=9
Perfect!
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y=2x
%286%29=2%2A%283%29
6=6
Bingo!
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That's it! Feel free to email if you have questions about this.
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Ms.Figgy
math.in.the.vortex@gmail.com