document.write( "Question 316554: Given the polynomial 3x^2-6x-18 what is the vertex of it's graph \n" ); document.write( "

Algebra.Com's Answer #226455 by josmiceli(19441) $\"\"$ $\"About$

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The vertex is midway between the 2 roots
\n" ); document.write( "When the equation is in the form
\n" ); document.write( " $\"ax%5E2+%2B+bx+%2B+c+=+0\"$
\n" ); document.write( "The formula to find roots is
\n" ); document.write( " $\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"$
\n" ); document.write( "Midway between the 2 roots is $\"x=+%28-b%29%2F%282a%29\"$
\n" ); document.write( " $\"3x%5E2+-+6x+-+18+=+0\"$
\n" ); document.write( "The x coordinate of the vertex is at $\"%28-%28-6%29%29%2F%282%2A3%29+=+1\"$
\n" ); document.write( " $\"y+=+3%2A1%5E2+-+6%2A1+-+18\"$
\n" ); document.write( " $\"y+=+3+-+6+-+18\"$
\n" ); document.write( " $\"y+=+-21\"$
\n" ); document.write( "The vertex is at (1,-21)
\n" ); document.write( "Here's the plot
\n" ); document.write( " $\"+graph%28+500%2C+500%2C+-10%2C+10%2C+-25%2C+10%2C+3x%5E2+-+6x+-+18%29+\"$ \n" ); document.write( "

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