Answer:
-4
Step-by-step explanation:
The direction of the parabola depends on the sign of the leading coefficient i.e. sign of the coefficient with the squared term.
Remember these two points for vertical parabola:
- If the leading coefficient is positive the parabola will always open upwards
- If the leading coefficient is negative the parabola will always open downwards
We are given that the parabola opens down. This means that the leading coefficient must be negative. Among the given options only one option contains a negative number i.e. -4.
Therefore, the missing coefficient could be -4
