document.write( "Question 122679: Solve by substitution\r
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Algebra.Com's Answer #90068 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "\"system%28x-5y=2%2C2x%2B3y=17%29\"\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-5y=2\" Start with the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"-5y=2-x\" Subtract \"x\" from both sides\r
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\n" ); document.write( "\n" ); document.write( "\"-5y=-x%2B2\" Rearrange the equation\r
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\n" ); document.write( "\n" ); document.write( "\"y=%28-x%2B2%29%2F%28-5%29\" Divide both sides by \"-5\"\r
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\n" ); document.write( "\n" ); document.write( "\"y=%28%28-1%29%2F%28-5%29%29x%2B%282%29%2F%28-5%29\" Break up the fraction\r
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\n" ); document.write( "\n" ); document.write( "\"y=%281%2F5%29x-2%2F5\" Reduce\r
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\n" ); document.write( "\n" ); document.write( "Since \"y=%281%2F5%29x-2%2F5\", we can now replace each \"y\" in the second equation with \"%281%2F5%29x-2%2F5\" to solve for \"x\"\r
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\n" ); document.write( "\n" ); document.write( "\"2x%2B3highlight%28%28%281%2F5%29x-2%2F5%29%29=17\" Plug in \"y=%281%2F5%29x-2%2F5\" into the first equation. In other words, replace each \"y\" with \"%281%2F5%29x-2%2F5\". 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( "\"2x%2B%283%29%281%2F5%29x%2B%283%29%28-2%2F5%29=17\" Distribute \"3\" to \"%281%2F5%29x-2%2F5\"\r
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\n" ); document.write( "\n" ); document.write( "\"2x%2B%283%2F5%29x-6%2F5=17\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"%285%29%282x%2B%283%2F5%29x-6%2F5%29=%285%29%2817%29\" Multiply both sides by the LCM of 5. This will eliminate the fractions (note: if you need help with finding the LCM, check out this solver)\r
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\n" ); document.write( "\n" ); document.write( "\"10x%2B3x-6=85\" Distribute and multiply the LCM to each side\r
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\n" ); document.write( "\n" ); document.write( "\"13x-6=85\" Combine like terms on the left side\r
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\n" ); document.write( "\n" ); document.write( "\"13x=85%2B6\"Add 6 to both sides\r
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\n" ); document.write( "\n" ); document.write( "\"13x=91\" Combine like terms on the right side\r
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\n" ); document.write( "\n" ); document.write( "\"x=%2891%29%2F%2813%29\" Divide both sides by 13 to isolate x\r
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\n" ); document.write( "\n" ); document.write( "\"x=7\" 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=7\"\r
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\n" ); document.write( "\n" ); document.write( "Since we know that \"x=7\" we can plug it into the equation \"y=%281%2F5%29x-2%2F5\" (remember we previously solved for \"y\" in the first equation).\r
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\n" ); document.write( "\n" ); document.write( "\"y=%281%2F5%29x-2%2F5\" Start with the equation where \"y\" was previously isolated.\r
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\n" ); document.write( "\n" ); document.write( "\"y=%281%2F5%29%287%29-2%2F5\" Plug in \"x=7\"\r
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\n" ); document.write( "\n" ); document.write( "\"y=7%2F5-2%2F5\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"y=1\" Combine like terms and reduce. (note: if you need help with fractions, check out this solver)\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 our answers are:\r
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\n" ); document.write( "\n" ); document.write( "\"x=7\" and \"y=1\"\r
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\n" ); document.write( "\n" ); document.write( "which form the point \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 \"x-5y=2\" (red) and \"2x%2B3y=17\" (green) and the intersection of the lines (blue circle).\r
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