document.write( "Question 170001: This is a systems of equations question. \r
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\n" ); document.write( "\n" ); document.write( "Please solve by substitution, elimination, AND graphing. ( the same equation) \r
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Algebra.Com's Answer #125462 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "Table of Contents:\r
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Substitution
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Jump to Top\r
\n" ); document.write( "\n" ); document.write( "Substitution:\r
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\n" ); document.write( "\n" ); document.write( "Note: the first equation \"2x%2B6=y\" is the same as \"y=2x%2B6\"\r
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\n" ); document.write( "\n" ); document.write( "\"3x%2B4y=24\" Start with the second equation\r
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\n" ); document.write( "\n" ); document.write( "\"3x%2B4%282x%2B6%29=24\" Plug in \"y=2x%2B6\"\r
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\n" ); document.write( "\n" ); document.write( "\"3x%2B8x%2B24=24\" Distribute.\r
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\n" ); document.write( "\n" ); document.write( "\"11x%2B24=24\" Combine like terms on the left side.\r
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\n" ); document.write( "\n" ); document.write( "\"11x=24-24\" Subtract \"24\" from both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"11x=0\" Combine like terms on the right side.\r
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\n" ); document.write( "\n" ); document.write( "\"x=%280%29%2F%2811%29\" Divide both sides by \"11\" to isolate \"x\".\r
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\n" ); document.write( "\n" ); document.write( "\"x=0\" Reduce. So this is the first part of the answer.\r
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\n" ); document.write( "\n" ); document.write( "\"y=2x%2B6\" Go back to the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"y=2%280%29%2B6\" Plug in \"x=0\".\r
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\n" ); document.write( "\n" ); document.write( "\"y=0%2B6\" Multiply \"2\" and \"0\" to get \"0\".\r
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\n" ); document.write( "\n" ); document.write( "\"y=6\" Combine like terms. This is the second part of the answer.\r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So the solutions are \"x=0\" and \"y=6\"\r
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\n" ); document.write( "\n" ); document.write( "Which forms the ordered pair (0,6)\r
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Jump to Top\r
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\n" ); document.write( "\n" ); document.write( "\"2x%2B6=y\" Start with the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"2x=y-6\" Subtract 6 from both sides\r
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\n" ); document.write( "\n" ); document.write( "\"2x-y=-6\" Subtract \"y\" from both sides\r
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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%282x-y=-6%2C3x%2B4y=24%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"4%282x-y%29=4%28-6%29\" Multiply the both sides of the first equation by 4.\r
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\n" ); document.write( "\n" ); document.write( "\"8x-4y=-24\" Distribute and multiply.\r
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\n" ); document.write( "\n" ); document.write( "So we have the new system of equations:\r
\n" ); document.write( "\n" ); document.write( "\"system%288x-4y=-24%2C3x%2B4y=24%29\"\r
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\n" ); document.write( "\n" ); document.write( "Now 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( "\"%288x-4y%29%2B%283x%2B4y%29=%28-24%29%2B%2824%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"%288x%2B3x%29%2B%28-4y%2B4y%29=-24%2B24\" Group like terms.\r
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\n" ); document.write( "\n" ); document.write( "\"11x%2B0y=0\" Combine like terms. Notice how the y terms cancel out.\r
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\n" ); document.write( "\n" ); document.write( "\"11x=0\" Simplify.\r
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\n" ); document.write( "\n" ); document.write( "\"x=%280%29%2F%2811%29\" Divide both sides by \"11\" to isolate \"x\".\r
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\n" ); document.write( "\n" ); document.write( "\"8x-4y=-24\" Now go back to the first equation.\r
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\n" ); document.write( "\n" ); document.write( "\"8%280%29-4y=-24\" Plug in \"x=0\".\r
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\n" ); document.write( "\n" ); document.write( "\"0-4y=-24\" Multiply.\r
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\n" ); document.write( "\n" ); document.write( "\"-4y=-24\" Remove any zero terms.\r
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\n" ); document.write( "\n" ); document.write( "\"y=%28-24%29%2F%28-4%29\" Divide both sides by \"-4\" to isolate \"y\".\r
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\n" ); document.write( "\n" ); document.write( "\"y=6\" Reduce.\r
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\n" ); document.write( "\n" ); document.write( "So our answers are \"x=0\" and \"y=6\".\r
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\n" ); document.write( "\n" ); document.write( "Which form the ordered pair . Note: this is the same answer as before.\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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Jump to Top\r
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\n" ); document.write( "\n" ); document.write( "\"2x%2B6=y\" Start with the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"y=2x%2B6\" Rearrange the equation\r
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\n" ); document.write( "\n" ); document.write( "Looking at \"y=2x%2B6\" we can see that the equation is in slope-intercept form \"y=mx%2Bb\" where the slope is \"m=2\" and the y-intercept is \"b=6\" \r
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\n" ); document.write( "\n" ); document.write( "Since \"b=6\" this tells us that the y-intercept is .Remember the y-intercept is the point where the graph intersects with the y-axis\r
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\n" ); document.write( "\n" ); document.write( "So we have one point \r
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\n" ); document.write( "\n" ); document.write( "Now since the slope is comprised of the \"rise\" over the \"run\" this means\r
\n" ); document.write( "\n" ); document.write( "\"slope=rise%2Frun\"\r
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\n" ); document.write( "\n" ); document.write( "Also, because the slope is \"2\", this means:\r
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\n" ); document.write( "\n" ); document.write( "\"rise%2Frun=2%2F1\"\r
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\n" ); document.write( "\n" ); document.write( "which shows us that the rise is 2 and the run is 1. This means that to go from point to point, we can go up 2 and over 1\r
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\n" ); document.write( "\n" ); document.write( "So starting at , go up 2 units \r
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\n" ); document.write( "\n" ); document.write( "and to the right 1 unit to get to the next point \r
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\n" ); document.write( "\n" ); document.write( "Now draw a line through these points to graph \"y=2x%2B6\"\r
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\n" ); document.write( "\n" ); document.write( " So this is the graph of \"y=2x%2B6\" through the points and \r
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\n" ); document.write( "\n" ); document.write( "\"3x%2B4y=24\" Now move onto the second equation\r
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\n" ); document.write( "\n" ); document.write( "\"4y=24-3x\" Subtract \"3x\" from both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"4y=-3x%2B24\" Rearrange the terms.\r
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\n" ); document.write( "\n" ); document.write( "\"y=%28-3x%2B24%29%2F%284%29\" Divide both sides by \"4\" to isolate y.\r
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\n" ); document.write( "\n" ); document.write( "\"y=%28%28-3%29%2F%284%29%29x%2B%2824%29%2F%284%29\" Break up the fraction.\r
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\n" ); document.write( "\n" ); document.write( "\"y=-%283%2F4%29x%2B6\" Reduce.\r
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\n" ); document.write( "\n" ); document.write( "Looking at \"y=-%283%2F4%29x%2B6\" we can see that the equation is in slope-intercept form \"y=mx%2Bb\" where the slope is \"m=-3%2F4\" and the y-intercept is \"b=6\" \r
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\n" ); document.write( "\n" ); document.write( "Since \"b=6\" this tells us that the y-intercept is .Remember the y-intercept is the point where the graph intersects with the y-axis\r
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\n" ); document.write( "\n" ); document.write( "So we have one point \r
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\n" ); document.write( "\n" ); document.write( "Now since the slope is comprised of the \"rise\" over the \"run\" this means\r
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\n" ); document.write( "\n" ); document.write( "Also, because the slope is \"-3%2F4\", this means:\r
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\n" ); document.write( "\n" ); document.write( "\"rise%2Frun=-3%2F4\"\r
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\n" ); document.write( "\n" ); document.write( "which shows us that the rise is -3 and the run is 4. This means that to go from point to point, we can go down 3 and over 4\r
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\n" ); document.write( "\n" ); document.write( "So starting at , go down 3 units \r
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\n" ); document.write( "\n" ); document.write( "and to the right 4 units to get to the next point \r
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\n" ); document.write( "\n" ); document.write( "Now draw a line through these points to graph \"y=-%283%2F4%29x%2B6\"\r
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\n" ); document.write( "\n" ); document.write( " So this is the graph of \"y=-%283%2F4%29x%2B6\" through the points and \r
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\n" ); document.write( "\n" ); document.write( "Now let's graph the two equations together on the same coordinate system:\r
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\n" ); document.write( "\n" ); document.write( " Graph of \"y=2x%2B6\" (red) and graph of \"y=-%283%2F4%29x%2B6\" (green)\r
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\n" ); document.write( "\n" ); document.write( "Notice how the two lines intersect at the point (0,6). So this means that the solution is \"x=0\" and \"y=6\" (which confirms our previous answers)
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