Average rate of change for f(x) = –2x^2 + 5x – 2 on [-1, 1].

[Don509]

Average rate of change for f(x) = –2x^2 + 5x – 2 on [-1, 1].

Find the average rate of change for f(x) = –2x² + 5x – 2 on [-1, 1].

I began by factoring and got (-2x+1)(x-2)

I don't know what to do from there.

I substituted -1 for x but got nowhere.

The correct solution is 5 but I don't know how.

 

[Deleted member 4993]

Find the average rate of change for f(x) = –2x² + 5x – 2 on [-1, 1].

I began by factoring and got (-2x+1)(x-2)

I don't know what to do from there.

I substituted -1 for x but got nowhere.

The correct solution is 5 but I don't know how.

Factoring is not needed here!

Do you know the definition of average rate of change of a function [f(x)] between two points x₁ and x₂?

What does your class-notes say? What does your text-book say?

 

[stapel]

Find the average rate of change for f(x) = –2x² + 5x – 2 on [-1, 1].

I began by factoring and got (-2x+1)(x-2)

Why? You're not "solving for the zeroes" or anything similar. Instead, try working with what you know:

If you're trying to find the average rate of change in something, don't you take the starting value, the ending value, and the time interval over which the change occurred? And then do some simple arithmetic to these values? Try applying that thinking here.