document.write( "Question 1142378: The graph of y = 5 + 9x − 2x^2\r
\n" ); document.write( "\n" ); document.write( "1. opens downwards and has vertex 2(1/4), 15(1/8)
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\n" ); document.write( "3. opens downwards and has vertex −2(1/4), 15 (1/8)
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Algebra.Com's Answer #763084 by ikleyn(52915) $\"\"$ $\"About$

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document.write( "Since the coefficient at x^2 is negative (its value is -2), the graph opens downwards.\r\n" );
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document.write( "The x- coordinate of the vertex is  x=  (referring to the standard form of the quadratic function y = ax^2 + bx + c,\r\n" );
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document.write( "in which  a= -2, b= 9).\r\n" );
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document.write( "Thus the x- coordinate of the vertex is  x=  =  =   in this case.\r\n" );
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document.write( "Among the given 5 optional answers, only n1 satisfies these conditions -- so, only n1 is the potential candidate.\r\n" );
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document.write( "Now substitute  x=    into the formula of the parabola to verify that y  then equals  .\r\n" );
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document.write( "Do this last check on your own.\r\n" );
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