document.write( "Question 609154: Y=2x(squared)-8x-1
\n" ); document.write( "i wanna know the a vaule b vaule and c vaule i also wanna know if it opens up or down? the axis of symmetry the vertex the domain and the range \n" ); document.write( "

Algebra.Com's Answer #383583 by Edwin McCravy(20055) $\"\"$ $\"About$

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document.write( "I do it the \"vertex formula\" way\r\n" );
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document.write( "y = 2x² - 8x - 1\r\n" );
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document.write( "Compare your equation to this model:\r\n" );
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document.write( "y = ax² + bx + c\r\n" );
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document.write( "It's easy to see that a=2, b=-8, c = -1\r\n" );
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document.write( "We know that it opens upward because \"a\" is a positive number.\r\n" );
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document.write( "The vertex formula is:\r\n" );
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document.write( "The vertex or turning point is (h,k) where h =  and \r\n" );
document.write( "k = ah²+bh+c  and the axis of symmetry is the vertical line whose \r\n" );
document.write( "equation is x = h\r\n" );
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document.write( "So for your vertex, h =  =  = 2\r\n" );
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document.write( "and k = ah²+bh+c = (2)(2)²+(-8)(2)+(-1) = 2(4)-16-1 = 8-16-1 = -9 \r\n" );
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document.write( "So the vertex is (h,k) = (2,-9) \r\n" );
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document.write( "The y-intercept is found by letting x=0 in the original equation:\r\n" );
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document.write( "    y = 2x² - 8x - 1\r\n" );
document.write( "    y = 2(0)² - 8(0) - 1\r\n" );
document.write( "    y = -1\r\n" );
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document.write( "The y-intercept is the point (0,-1)\r\n" );
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document.write( "So we plot the vertex the axis of symmetry and the y-intercept:\r\n" );
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document.write( "Now you can draw in the parabola so that it is symmetrical with\r\n" );
document.write( "the green line of symmetry.\r\n" );
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document.write( "All x-values are in the domain, so the domain is all reals (, )\r\n" );
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document.write( "The only y-values are those from the vertex which is -9 upward, \r\n" );
document.write( "so the range is (-9,).\r\n" );
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document.write( "Edwin

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