Question 320758
Complete the square to get into vertex form, {{{y=a(x-h)^2+k}}} where the (h,k) is the vertex.
{{{f(x)=3x^2-12x+21}}}
{{{f(x)=3(x^2-4x)+21}}}
{{{f(x)=3(x^2-4x+4)+21-12}}}
{{{f(x)=3(x-2)^2+9}}}
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(2,9)