Question 362086
Use the vertex form of a parabola,
{{{y=a(x-h)^2+k}}} where ({{{h}}},{{{k}}}) is the vertex.
{{{y=a(x-2)^2-4}}}
Now use the point (8,6) to solve for {{{a}}}.
{{{6=a(8-2)^2-4}}}
{{{10=a(6)^2}}}
{{{a=10/36}}
{{{a=5/18}}}
{{{y=(5/18)(x-2)^2-4}}}
{{{y=(5/18)(x^2-4x+4)-4}}}
{{{y=(5/18)x^2-(10/9)x+(10/9)-(36/9)}}}
{{{highlight(y=(5/18)x^2-(10/9)x-(26/9))}}}