document.write( "Question 1047916: Find the greatest value of each function.
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\n" ); document.write( "Please demonstrate with steps.
\n" ); document.write( "I need lots of help on this.
\n" ); document.write( "My teacher just introduced me to quadratic funtions and I don't understand.
\n" ); document.write( "Thank you very much.
\n" ); document.write( "God bless you. \n" ); document.write( "

Algebra.Com's Answer #663485 by AnlytcPhil(1806) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "Watch this video to learn about quadratic functions.\r\n" );
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document.write( "https://www.youtube.com/watch?v=QJU-nfaTSto\r\n" );
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document.write( "y = -x^2-3x\r\n" );
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document.write( "compare to y = ax^2+bx+c\r\n" );
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document.write( "a=-1, b=-3, c=0\r\n" );
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document.write( "It opens downward because a is negative.\r\n" );
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document.write( "The greatest value is found at the vertex.\r\n" );
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document.write( "the x-coordinate of the vertex is -b/(2a)\r\n" );
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document.write( "-(-3)/(2*-1) = -3/2\r\n" );
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document.write( "Find the y-coordinate on the vertex by substituting\r\n" );
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document.write( "y = -x^2-3x\r\n" );
document.write( "y = -(-3/2)^2-3(-3/2)\r\n" );
document.write( "y = -9/4+9/2\r\n" );
document.write( "y = -9/4+18/4\r\n" );
document.write( "y = 9/4\r\n" );
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document.write( "So the vertex is the point (-3/2, 9/4).\r\n" );
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document.write( "And the y-value of the vertex is the greatest value of\r\n" );
document.write( "the function if the graph opens downward, and the least\r\n" );
document.write( "value if the graph opens upward.\r\n" );
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document.write( "So the greatest value is 9/4 or 2.25.\r\n" );
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document.write( "Here's the graph with the vertex at the top.\r\n" );
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document.write( "Edwin

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