Answer:
The equation of the parabola is  .  The average rate of change of the parabola is -4.
.  The average rate of change of the parabola is -4.
Step-by-step explanation:
We must remember that a parabola is represented by a quadratic function, which can be formed by knowing three different points. A quadratic function is standard form is represented by:

Where:
 - Independent variable, dimensionless.
 - Independent variable, dimensionless.
 - Dependent variable, dimensionless.
 - Dependent variable, dimensionless.
 ,
,  ,
,  - Coefficients, dimensionless.
 - Coefficients, dimensionless.
If we know that  ,
,  and
 and  are part of the parabola, the following linear system of equations is formed:
 are part of the parabola, the following linear system of equations is formed:



This system can be solved both by algebraic means (substitution, elimination, equalization, determinant) and by numerical methods. The solution of the linear system is:
 ,
,  ,
,  .
. 
The equation of the parabola is  .
. 
Now, we calculate the average rate of change ( ), dimensionless, between
), dimensionless, between  and
 and  by using the formula of secant line slope:
 by using the formula of secant line slope:










The average rate of change of the parabola is -4.