document.write( "Question 1008730: Find an equation of the plane that passes through the points
\n" ); document.write( "(-1, 0, -4),(2, 1, 8),and(-1, 1, -1).(Suggestion: The equation of a plane can be written as z = ax + by + c.)\r
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Algebra.Com's Answer #624354 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "z = ax + by + c\r\n" );
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document.write( "Substitute (x, y, z) = (-1, 0, -4)\r\n" );
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document.write( "        -4 = a(-1) + b(0) + c\r\n" );
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document.write( "        -4 = -a + c\r\n" );
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document.write( "     a - c = 4\r\n" );
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document.write( "Substitute (x, y, z) = (2, 1, 8)\r\n" );
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document.write( "          8 = a(2) + b(1) + c\r\n" );
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document.write( "          8 = 2a + b + c\r\n" );
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document.write( "-2a - b - c = -8\r\n" );
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document.write( " 2a + b + c = 8\r\n" );
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document.write( "Substitute (x, y, z) = (-1, 1, -1)\r\n" );
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document.write( "        -1 = a(-1) + b(1) + c\r\n" );
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document.write( "        -1 = -a + b + c\r\n" );
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document.write( " a - b - c = 1\r\n" );
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document.write( "So we have this system of equations:\r\n" );
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document.write( "That's easy to solve for a, b, and c.\r\n" );
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document.write( "The substitute the vales you get for a,b, and c\r\n" );
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document.write( "in z = ax + by + c to get your answer.\r\n" );
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document.write( "Want to see your plane graphed in 3D?  Look below.\r\n" );
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document.write( "It's the plane in which the green triangle is in. \r\n" );
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document.write( "Edwin
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