document.write( "Question 1048459: y=3x^2 + 15x + 9\r
\n" ); document.write( "\n" ); document.write( "Find the vertex and if it is maximum or minimum \r
\n" ); document.write( "\n" ); document.write( "Do it by finding the square please! \n" ); document.write( "
Algebra.Com's Answer #664041 by rothauserc(4718)\"\" \"About 
You can put this solution on YOUR website!
y = 3x^2 + 15x + 9
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\n" ); document.write( "y - 9 = 3x^2 + 15x
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\n" ); document.write( "y - 9 = 3(x^2 +5x)
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\n" ); document.write( "y - 9 + 3(25/4) = 3(x^2 +5x + 25/4)
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\n" ); document.write( "y - 36/4 + 75/4 = 3(x + 5/2)^2
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\n" ); document.write( "y + 39/4 = 3(x + 5/2)^2
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\n" ); document.write( "y = 3(x + 5/2)^2 - 39/4
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\n" ); document.write( "y = 3( x - (-5/2))^2 - 39/4
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\n" ); document.write( "vertex is at (-5/2, -39/4) which is a minimum
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\n" ); document.write( "we can check this by using
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\n" ); document.write( "x = -b/2a = -15 / 6 = -5/2
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\n" ); document.write( "y = 3(-5/2)^2 + 15(-5/2) + 9
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\n" ); document.write( "y = 75/4 -150/4 + 36/4 = -39/4
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\n" ); document.write( "our answer (-5/2, -39/4) checks
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