Pls give explanation from differentiation method -CAT 04 = 53. Let f(x) = ax 2 – b| x|, where a and b are constants. Then at x = 0, f(x) is

1) 1. maximised whenever a > 0, b > 0
2) 2. maximised whenever a > 0, b < 0
3) 3. minimized whenever a > 0, b > 0
4) 4. minimized whenever a > 0, b < 0