Question 1181407
If using as {{{y=a(x-h)^2+k}}}, then your given vertex gives a starting equation {{{y=a(x-1)^2+1}}}.


The included point which the parabola passes through means {{{-1=a(2-1)^2+1}}};
{{{-1=a(1)^2+1}}}
{{{-1=a+1}}}
{{{a=-2}}}



Equation for the parabola:
{{{highlight(y=-2(x-1)^2+1)}}}