Question 1032297
You should be able to take advantage of the given root and the easily found symmetry axis with the use of the standard form equation.


Two x values give the same y value of {{{-20}}}.  This tells you where the symmetry axis is.


{{{y=a(x-1)^2+k}}}----a starter equation


Point (-2,-20) gives {{{a*((-2)-1)^2+k=-20}}}
and
point  (4,-20) gives {{{a((4)-1)^2+k=-20}}}
and the system easily solvable.