Question 596080
Hi, there--
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We can use the the substitution method to solve this system.
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{{{x+y=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+y=9}}}
{{{x+2x=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(3)}}}
{{{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+y=9}}} 
{{{(3)+(6)=9}}}
{{{9=9}}}
Perfect!
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{{{y=2x}}}
{{{(6)=2*(3)}}}
{{{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