# Precalculus -- determine the rate of change of the function

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1. Feb 1, 2015

### Niaboc67

1. The problem statement, all variables and given/known data

2. Relevant equations
Rate of change formula: y2-y1/x2-y2

3. The attempt at a solution
If this is a rate of change problem so I use the rate of change formula: y2-y1/x2-y2
and since it's from 2 to 4 I think that would be (2,0) (4,0)
and thus (0-0)/(4-2) = 0/2 = 0

I don't think this is right. What am I doing wrong?

2. Feb 1, 2015

### Staff: Mentor

Your formula needs parentheses, though. y2 - y1/x2 - x1 means $y_2 - \frac{y_1}{x_2} - x_1$.

3. Feb 2, 2015

### Brian T

Yes, your are correct. Since it is a curved function and we are taking the rate of change on that curved interval, it will give us the average rate of change. If you start at zero, and end at zero, on average your rate of change is 0.

4. Feb 2, 2015

### epenguin

If you start at anything and end at the same thing the averge rate of change is zero, but they have given you a simple example. :D