document.write( "Question 1113237: The vertex of a parabola is (-2, -20), and its y-intercept is (0, -12).\r
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Algebra.Com's Answer #728227 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
The vertex of a parabola is (-2, -20), and its y-intercept is (0, -12).
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document.write( "We draw the approximate graph, using what is given:\r\n" );
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document.write( "The standard form of a quadratic parabola is\r\n" );
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document.write( "\"y=a%28x-h%5E%22%22%29%5E2%2Bk\", where (h,k) is the vertex.\r\n" );
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document.write( "Since it is given that the vertex (h,k) = (-2, -20),\r\n" );
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document.write( "h = -2, and k = -20.\r\n" );
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document.write( "And since it passes through the point (0, -12),\r\n" );
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document.write( "x = 0 and y = -12\r\n" );
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document.write( "Substituting in\r\n" );
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document.write( "\"y=a%28x-h%5E%22%22%29%5E2%2Bk\",\r\n" );
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document.write( "\"-12=a%280-%28-2%29%5E%22%22%29%5E2%2B%28-20%29\"\r\n" );
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document.write( "\"-12=a%280%2B2%5E%22%22%29%5E2-20\"\r\n" );
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document.write( "\"-12=a%282%5E%22%22%29%5E2-20\"\r\n" );
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document.write( "\"-12=a%284%29-20\"\r\n" );
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document.write( "\"-12=4a-20\"\r\n" );
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document.write( "\"8=4a\"\r\n" );
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document.write( "\"2=a\"\r\n" );
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document.write( "Now go back to the standard form:\r\n" );
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document.write( "\"y=a%28x-h%5E%22%22%29%5E2%2Bk\"\r\n" );
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document.write( "Substitute a = 2, h = -2, k = -20\r\n" );
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document.write( "However this time, we do not substitute anything\r\n" );
document.write( "for x and y, for we want to leave them as variables:\r\n" );
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document.write( "\"y=a%28x-h%5E%22%22%29%5E2%2Bk\"\r\n" );
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document.write( "\"y=2%28x-%28-2%29%5E%22%22%29%5E2%2B%28-20%29\"\r\n" );
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document.write( "Then we simplify:\r\n" );
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document.write( "\"y=2%28x%2B2%5E%22%22%29%5E2-20\"\r\n" );
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document.write( "\"y=2%28x%2B2%5E%22%22%29%28x%2B2%5E%22%22%29-20\"\r\n" );
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document.write( "\"y=2%28x%5E2%2B4x%2B4%29-20\"\r\n" );
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document.write( "\"y=2x%5E2%2B8x%2B8-20\"\r\n" );
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document.write( "\"y=2x%5E2%2B8x-12\"\r\n" );
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document.write( "Edwin
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