Question 327874
Complete the square to put parabola in vertex form, {{{y=a(x-h)^2+k}}} where (h,k) i the vertex.
{{{y = 0.5x^2 - 8.7 x + 3}}}
{{{y=0.5(x^2-17.4x)+3}}}
{{{y=0.5(x^2-17.4x+8.7^2)+3-0.5(8.7)^2}}}
{{{y=0.5(x-8.7)^2+3-37.845}}}
{{{y=0.5(x-8.7)^2-34.845}}}
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The vertex is (8.7,-34.845).
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{{{drawing(300,300,-2,14,-40,10,grid(1),circle(8.7,-34.845,.35),graph(300,300,-2,14,-40,10,0.5x^2-8.7x+3))}}}