1. Feb 13, 2007

### championnn

they ask me to find the average rate of change from x=1 to x=2 in the equation x-2x^2

this is what I did

2-2(1)^2/2-1 = 0/1= 0

is that right?

thanks

2. Feb 13, 2007

### Integral

Staff Emeritus
It is difficult to tell just what you did.

Average rate of change would be something like:

$$\frac {F(x_1) - F(x_2)} { x_1 -x_2}$$

$$F(x) = x - 2x^2$$

Keep in mind, that x is common in that expression, the first x must equal the 2nd x.

3. Feb 14, 2007

### HallsofIvy

What you wrote, even if the calculations are correct, is meaningless.
First, I suspect you MEAN (2- 2(1)^2)/2- 1, not what you wrote.

In any case, you need to write "the average rate of change is ... " so someone reading this will know what you are doing.

What is the value of the function when x= 1?
What is the value of the function when x= 2?

What is the change in the value?

What is the average rate of change?

It strongly urge you to get into the habit of writing your work one step at a time like that. It will make it clearer to others what you are doing and, hopefully, make more sense to you (and probably give your teacher a heart attack!).