Question 316554
Complete the square to convert to vertex form,
{{{y=a(x-h)^2+k}}}
where (h,k) is the vertex.
{{{y=3x^2-6x-18}}}
{{{y=3(x^2-2x)-18}}}
{{{y=3(x^2-2x+1)-18-3}}}
{{{y=3(x-1)^2-21}}}
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(1,-21) is the vertex.
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{{{ drawing( 300, 300, -5, 5, -30, 20, grid(1),circle(1,-21,.3),graph( 300, 300, -5, 5, -30, 20, 3x^2-6x-18 )) }}}