document.write( "Question 118946: A quadratic equation is given by y=2x^2 - 6bx+3.What is the value of 'b' if the equation of the axis of symmetry is x=9 ? I think the answer is 6 but I really don't fully understand, can someone please explain this to me ? \n" ); document.write( "

Algebra.Com's Answer #87073 by scott8148(6628) $\"\"$ $\"About$

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for a quadratic of the form ax^2+bx+c, the equation for the axis of symmetry is x=-b/2a\r
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\n" ); document.write( "\n" ); document.write( "in this case 9=-(-6b)/(2*2) __ 36=6b __ 6=b\r
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\n" ); document.write( "\n" ); document.write( "looking at the quadratic formula can help to clarify
\n" ); document.write( "___ the formula gives two solutions $\"%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F2a\"$ and $\"%28-b-sqrt%28b%5E2-4ac%29%29%2F2a\"$ \r
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\n" ); document.write( "\n" ); document.write( "the average of the two solutions (which is the midline of the graph) is -b/2a
\n" ); document.write( "__ the square root portions cancel each other \n" ); document.write( "

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