For this case we have the following system of equations:

We multiply the first equation by -4:

We have the following equivalent system of equations:

We add the equations:

We find the value of the variable "x":

Thus, the solution of the system is:

See the graphic in the attached image
ANswer:

See the graphic in the attached image
D is distance-*2 meters* in 3 hours
Answer:
{(3,-2), (4,-2),(5,-2), (6,-2)} this relation is not a function.
Our parabola open downward and therefore a is negative.
Explanation:
As value of a changes from positive to negative or from negative to positive, the direction of opening changes. For negative values of a we got negative parabolas that open downward. As the original formula y = x^2 we see that x^2 will always be positive because when you square a number it always gives positive value. Therefore the direction for which it will open, depends on value of a.