document.write( "Question 174867: This question confused me.\r
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Algebra.Com's Answer #129933 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
\"2%28x%2B1%29-%28y-4%29=15\" Start with the first equation.\r
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\n" ); document.write( "\n" ); document.write( "\"2x%2B2-y%2B4=15\" Distribute\r
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\n" ); document.write( "\n" ); document.write( "\"2x-y%2B6=15\" Combine like terms.\r
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\n" ); document.write( "\n" ); document.write( "\"2x-y=15-6\" Subtract 6 from both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"2x-y=9\" Combine like terms. \r
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\n" ); document.write( "\n" ); document.write( "\"3%28x-1%29%2B4%28y%2B2%29=2\" Move onto the second equation.\r
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\n" ); document.write( "\n" ); document.write( "\"3x-3%2B4y%2B8=2\" Distribute\r
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\n" ); document.write( "\n" ); document.write( "\"3x%2B4y%2B5=2\" Combine like terms.\r
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\n" ); document.write( "\n" ); document.write( "\"3x%2B4y=2-5\" Subtract 5 from both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"3x%2B4y=-3\" Combine like terms.\r
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\n" ); document.write( "\n" ); document.write( "So we have the system of equations:\r
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\n" ); document.write( "\n" ); document.write( "\"system%282x-y=9%2C3x%2B4y=-3%29\"\r
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\n" ); document.write( "\n" ); document.write( "Let's solve this system by 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( "\"2x-y=9\" Start with the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"-y=9-2x\" Subtract \"2x\" from both sides\r
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\n" ); document.write( "\n" ); document.write( "\"-y=-2x%2B9\" Rearrange the equation\r
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\n" ); document.write( "\n" ); document.write( "\"y=%28-2x%2B9%29%2F%28-1%29\" Divide both sides by \"-1\"\r
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\n" ); document.write( "\n" ); document.write( "\"y=%28%28-2%29%2F%28-1%29%29x%2B%289%29%2F%28-1%29\" Break up the fraction\r
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\n" ); document.write( "\n" ); document.write( "\"y=2x-9\" Reduce\r
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\n" ); document.write( "\n" ); document.write( "Since \"y=2x-9\", we can now replace each \"y\" in the second equation with \"2x-9\" to solve for \"x\"\r
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\n" ); document.write( "\n" ); document.write( "\"3x%2B4highlight%28%282x-9%29%29=-3\" Plug in \"y=2x-9\" into the second equation. In other words, replace each \"y\" with \"2x-9\". 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( "\"3x%2B%284%29%282%29x%2B%284%29%28-9%29=-3\" Distribute \"4\" to \"2x-9\"\r
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\n" ); document.write( "\n" ); document.write( "\"3x%2B8x-36=-3\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"11x-36=-3\" Combine like terms on the left side\r
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\n" ); document.write( "\n" ); document.write( "\"11x=-3%2B36\"Add 36 to both sides\r
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\n" ); document.write( "\n" ); document.write( "\"11x=33\" Combine like terms on the right side\r
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\n" ); document.write( "\n" ); document.write( "\"x=%2833%29%2F%2811%29\" Divide both sides by 11 to isolate x\r
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\n" ); document.write( "\n" ); document.write( "\"x=3\" 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=3\"\r
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\n" ); document.write( "\n" ); document.write( "Since we know that \"x=3\" we can plug it into the equation \"y=2x-9\" (remember we previously solved for \"y\" in the first equation).\r
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\n" ); document.write( "\n" ); document.write( "\"y=2x-9\" Start with the equation where \"y\" was previously isolated.\r
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\n" ); document.write( "\n" ); document.write( "\"y=2%283%29-9\" Plug in \"x=3\"\r
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\n" ); document.write( "\n" ); document.write( "\"y=6-9\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"y=-3\" 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=-3\"\r
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\n" ); document.write( "\n" ); document.write( "-----------------Summary------------------------------\r
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\n" ); document.write( "\n" ); document.write( "So our answers are:\r
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\n" ); document.write( "\n" ); document.write( "\"x=3\" 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( "Now let's graph the two equations (if you need help with graphing, check out this solver)\r
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\n" ); document.write( "\n" ); document.write( "From the graph, we can see that the two equations intersect at . This visually verifies our answer.\r
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\n" ); document.write( "\n" ); document.write( " graph of \"2x-y=9\" (red) and \"3x%2B4y=-3\" (green) and the intersection of the lines (blue circle).\r
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