Ok... so this question can be solved by using simultaneous equations.
Use the general from of a parabola
[tex]y = ax^2 + bx + c[/tex]
you know the value of c, the y-intercept... y = -4
which means the equation is
[tex]y = ax^2 + bx - 4[/tex]
now use the other 2 points to get 2 equations in 2 unknowns
(-2, -20) just substitute
[tex]-20 = (-2)^2a + (-2)b - 4 ~~~or~~~ -20 = 4a - 2b - 4[/tex]
this becomes
[tex]4a - 2b = -16[/tex]
now the other equation using (4, -20)
The simplified form is
