Question 1021446
Equation not unique.  Vertex will be unknown point  (x,0).


Begin with {{{y=a(x-h)^2+0}}} same as {{{y=a(x-h)^2}}}.


Your one given point allows a possible equation in the unknown variables a and h, but not enough information to find their values, so you finish either with  {{{y=a(x-h)^2}}}  or  {{{system(3=a(4-h)^2,0=a(x-h)^2)}}}.