Quadratic

If f(0)=0 then 0=a(0)^2+b(0)+c, which means that c=0
If f(1)=2 then 2=a(1)^2+b(1), which means that a+b=2

If f(2)=-5 then -5=a(-5)^2+b(-5), which means that 25a-5b=-5, which means that b+5a=1

Solve the system of equations.

b+5a=1

b+a=2

4a=-1

a=-1/4

Solve for b and then plug in 3 for x. You should get your answer. Let me know if I did anything wrong!