Average Rate of Change for f(x) = 5x^2 - 8x from x = -1 to 4

[nesan]

Homework Statement

Consider the graph of the function f(x) = 5x^2 - 8x

Determine the average rate of change as x changes from -1 to 4

The Attempt at a Solution

f(4) - f(-1) / 4 - 1

The answer is not correct according to the answer sheet. :(

 

[Dick]

Homework Statement

Consider the graph of the function f(x) = 5x^2 - 8x

Determine the average rate of change as x changes from -1 to 4

The Attempt at a Solution

f(4) - f(-1) / 4 - 1

The answer is not correct according to the answer sheet. :(

Shouldn't your denominator be 4-(-1)?

 

[nesan]

GOD, KILL ME!

:"(

Thank you. Such a stupid mistake.

 

[Mark44]

In addition to what Dick said, you need more parentheses when you write out expressions like that in plain text.

f(4) - f(-1) / 4 - 1

This would be interpreted as f(4) - \frac{f(-1)}{4} - 1
If you write it on a single line, do it like this: (f(4) - f(-1))/(4 - (-1)).