document.write( "Question 1139595: The graph of a quadratic function opens downward with vertex at (3, 9). If the parabola passes through the origin, find the equation of the quadratic function. \n" ); document.write( "

Algebra.Com's Answer #760074 by ikleyn(52788) $\"\"$ $\"About$

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document.write( "Your quadratic function is\r\n" );
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document.write( "    f(x) =  + 9,\r\n" );
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document.write( "according to the condition,  where \"a\" is negative coefficient.\r\n" );
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document.write( "To find \"a\", use the second part of the condition: the parabola passes through the origin.\r\n" );
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document.write( "It means that f(0) = 0, i.e.\r\n" );
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document.write( "     + 9 = 0\r\n" );
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document.write( "     + 9 = 0\r\n" );
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document.write( "    9a = -9\r\n" );
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document.write( "    a =  = 1.\r\n" );
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document.write( "ANSWER.  The equation of the quadratic function is  f(x) =  + 9.\r\n" );
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