document.write( "Question 550485: HEEEEELLLPPPP please.....solve by the elimination method....... x + 4y = 21 and -x + 3y = 0.......type an ordered pair \n" ); document.write( "
Algebra.Com's Answer #358776 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "Start with the given system of equations:\r
\n" ); document.write( "\n" ); document.write( "\"system%28x%2B4y=21%2C-x%2B3y=0%29\"\r
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\n" ); document.write( "\n" ); document.write( "Add the equations together. You can do this by simply adding the two left sides and the two right sides separately like this:\r
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\n" ); document.write( "\n" ); document.write( "\"%28x%2B4y%29%2B%28-1x%2B3y%29=%2821%29%2B%280%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"%281x%2B-1x%29%2B%284y%2B3y%29=21%2B0\" Group like terms.\r
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\n" ); document.write( "\n" ); document.write( "\"0x%2B7y=21\" Combine like terms.\r
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\n" ); document.write( "\n" ); document.write( "\"7y=21\" Simplify.\r
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\n" ); document.write( "\n" ); document.write( "\"y=%2821%29%2F%287%29\" Divide both sides by \"7\" to isolate \"y\".\r
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\n" ); document.write( "\n" ); document.write( "\"y=3\" Reduce.\r
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\n" ); document.write( "\n" ); document.write( "\"x%2B4y=21\" Now go back to the first equation.\r
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\n" ); document.write( "\n" ); document.write( "\"x%2B4%283%29=21\" Plug in \"y=3\".\r
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\n" ); document.write( "\n" ); document.write( "\"x%2B12=21\" Multiply.\r
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\n" ); document.write( "\n" ); document.write( "\"x=21-12\" Subtract \"12\" from both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"x=9\" Combine like terms on the right side.\r
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\n" ); document.write( "\n" ); document.write( "So the solutions are \"x=9\" and \"y=3\".\r
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\n" ); document.write( "\n" ); document.write( "Which form the ordered pair .\r
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\n" ); document.write( "\n" ); document.write( "This means that the system is consistent and independent.\r
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\n" ); document.write( "\n" ); document.write( "Notice when we graph the equations, we see that they intersect at . So this visually verifies our answer.\r
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\n" ); document.write( "\n" ); document.write( " Graph of \"x%2B4y=21\" (red) and \"-x%2B3y=0\" (green) \r
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