Finding the value of an integral given a graph

[turbokaz]

Homework Statement

http://tinypic.com/view.php?pic=1xa2f&s=5 (this shows the graph that is related to the problem)
is the graph of an anti-derivative, F, of a
function f, use this graph to determine the value of I=∫ from 0 to 8 |f(x)|dx.
value of the definite integral

Homework Equations

The Attempt at a Solution

The answer choices are 11, 12, 13, 14, or 15. I have no idea how to get these answers. I looked at the graph and used Reimann Sum technique of counting up the squares, but I get numbers in the 20's. For absolute value functions, I know you switch any negative values to positive, but this whole function looks positive to me? Thoughts?

 

[ehild]

Hi turbokaz,

The plot is the antiderivative already, no need to integrate it further.
How do you calculate the definite integral between two points from the antiderivative?

What do you think about the sign of f(x)? In what domain is it positive and where is it negative?

ehild

 

[turbokaz]

F(b)-F(a)?
F(b) is 1, F(a) is 2. 1--2=3?

 

[turbokaz]

Bump...I'm still not getting anywhere

 

[turbokaz]

Nevermind. I understand the problem now. The answer is 11.

 

[ehild]

Congratulation!

ehild