document.write( "Question 200163: Hi!
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\n" ); document.write( "Use the elimination method to find all solutions of the system of equations. (Round each answer to two decimal places. Enter NONE in any unused answer blanks.) \r
\n" ); document.write( "\n" ); document.write( "{x^2-y^2=25
\n" ); document.write( " 2x^2-y^2=x+55\r
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Algebra.Com's Answer #150460 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
Start with the given system\r
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\n" ); document.write( "\n" ); document.write( "Multiply both sides of the first equation by -1\r
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\n" ); document.write( "\n" ); document.write( "\"system%28-1%28x%5E2-y%5E2%29=-1%2825%29%2C2x%5E2-y%5E2=x%2B55%29\"\r
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\n" ); document.write( "\n" ); document.write( "Distribute and multiply\r
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\n" ); document.write( "\n" ); document.write( "\"system%28-x%5E2%2By%5E2=-25%2C2x%5E2-y%5E2=x%2B55%29\"\r
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\n" ); document.write( "\n" ); document.write( "Now add the two equations\r
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\n" ); document.write( "\n" ); document.write( "\"%28-x%5E2%2By%5E2%29%2B%282x%5E2-y%5E2%29=-25%2Bx%2B55\"\r
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\n" ); document.write( "\n" ); document.write( "\"%28-x%5E2%2B2x%5E2%29%2B%28y%5E2-y%5E2%29=x%2B%28-25%2B55%29\" Group like terms.\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E2=x%2B30\" Combine like terms.\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E2-x-30=0\" Get all terms to the left side.\r
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\n" ); document.write( "\n" ); document.write( "Notice that the quadratic \"x%5E2-x-30\" is in the form of \"Ax%5E2%2BBx%2BC\" where \"A=1\", \"B=-1\", and \"C=-30\"\r
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\n" ); document.write( "\n" ); document.write( "Let's use the quadratic formula to solve for \"x\":\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-B+%2B-+sqrt%28+B%5E2-4AC+%29%29%2F%282A%29\" Start with the quadratic formula\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-%28-1%29+%2B-+sqrt%28+%28-1%29%5E2-4%281%29%28-30%29+%29%29%2F%282%281%29%29\" Plug in \"A=1\", \"B=-1\", and \"C=-30\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+%28-1%29%5E2-4%281%29%28-30%29+%29%29%2F%282%281%29%29\" Negate \"-1\" to get \"1\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+1-4%281%29%28-30%29+%29%29%2F%282%281%29%29\" Square \"-1\" to get \"1\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+1--120+%29%29%2F%282%281%29%29\" Multiply \"4%281%29%28-30%29\" to get \"-120\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+1%2B120+%29%29%2F%282%281%29%29\" Rewrite \"sqrt%281--120%29\" as \"sqrt%281%2B120%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+121+%29%29%2F%282%281%29%29\" Add \"1\" to \"120\" to get \"121\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+121+%29%29%2F%282%29\" Multiply \"2\" and \"1\" to get \"2\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+11%29%2F%282%29\" Take the square root of \"121\" to get \"11\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B+11%29%2F%282%29\" or \"x+=+%281+-+11%29%2F%282%29\" Break up the expression. \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2812%29%2F%282%29\" or \"x+=++%28-10%29%2F%282%29\" Combine like terms. \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+6\" or \"x+=+-5\" Simplify. \r
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\n" ); document.write( "\n" ); document.write( "So the solutions (for the x values) are \"x+=+6\" or \"x+=+-5\"\r
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\n" ); document.write( "\n" ); document.write( "Now take each x value and plug them into either equation to solve for \"y\". Let me know if you need more help from here.\r
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\n" ); document.write( "\n" ); document.write( "Note: In this case, you should get 4 ordered. However, one solution is repeated twice. So there are really only 3 ordered pair solutions.
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