document.write( "Question 173215This question is from textbook Amsco's integrated algerbra 1
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\n" ); document.write( "x-7=4\r
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Algebra.Com's Answer #128056 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
Note: I'm assuming that you left out the variable \"y\" in the second equation and it should look like \"x-7y=4\"\r
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\n" ); document.write( "\n" ); document.write( "Start with the given system of equations:\r
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\n" ); document.write( "\n" ); document.write( "\"system%28x%2By=12%2Cx-7y=4%29\"\r
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\n" ); document.write( "\n" ); document.write( "Let's solve this system by use of substitution\r
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\n" ); document.write( "\n" ); document.write( "Now in order to solve this system by using substitution, we need to solve (or isolate) one variable. I'm going to solve for y.\r
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\n" ); document.write( "\n" ); document.write( "So let's isolate y in the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"x%2By=12\" Start with the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"y=12-x\" Subtract \"x\" from both sides\r
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\n" ); document.write( "\n" ); document.write( "\"y=-x%2B12\" Rearrange the equation\r
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\n" ); document.write( "\n" ); document.write( "Since \"y=-x%2B12\", we can now replace each \"y\" in the second equation with \"-x%2B12\" to solve for \"x\"\r
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\n" ); document.write( "\n" ); document.write( "\"x-7highlight%28%28-x%2B12%29%29=4\" Plug in \"y=-x%2B12\" into the second equation. In other words, replace each \"y\" with \"-x%2B12\". Notice we've eliminated the \"y\" variables. So we now have a simple equation with one unknown.\r
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\n" ); document.write( "\n" ); document.write( "\"x%2B%28-7%29%28-1%29x%2B%28-7%29%2812%29=4\" Distribute \"-7\" to \"-x%2B12\"\r
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\n" ); document.write( "\n" ); document.write( "\"x%2B7x-84=4\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"8x-84=4\" Combine like terms on the left side\r
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\n" ); document.write( "\n" ); document.write( "\"8x=4%2B84\"Add 84 to both sides\r
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\n" ); document.write( "\n" ); document.write( "\"8x=88\" Combine like terms on the right side\r
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\n" ); document.write( "\n" ); document.write( "\"x=%2888%29%2F%288%29\" Divide both sides by 8 to isolate x\r
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\n" ); document.write( "\n" ); document.write( "\"x=11\" Divide\r
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\n" ); document.write( "\n" ); document.write( "-----------------First Answer------------------------------\r
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\n" ); document.write( "\n" ); document.write( "So the first part of our answer is: \"x=11\"\r
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\n" ); document.write( "\n" ); document.write( "Since we know that \"x=11\" we can plug it into the equation \"y=-x%2B12\" (remember we previously solved for \"y\" in the first equation).\r
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\n" ); document.write( "\n" ); document.write( "\"y=-x%2B12\" Start with the equation where \"y\" was previously isolated.\r
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\n" ); document.write( "\n" ); document.write( "\"y=-%2811%29%2B12\" Plug in \"x=11\"\r
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\n" ); document.write( "\n" ); document.write( "\"y=-11%2B12\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"y=1\" Combine like terms \r
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\n" ); document.write( "\n" ); document.write( "-----------------Second Answer------------------------------\r
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\n" ); document.write( "\n" ); document.write( "So the second part of our answer is: \"y=1\"\r
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\n" ); document.write( "\n" ); document.write( "-----------------Summary------------------------------\r
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\n" ); document.write( "\n" ); document.write( "So the solutions are:\r
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\n" ); document.write( "\n" ); document.write( "\"x=11\" and \"y=1\"\r
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\n" ); document.write( "\n" ); document.write( "which form the ordered pair \r
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