In this second example,
we will find the area under the line y = 2.5  x from
x = 0 to x = 5.
This is a little trickier than the first example since there is a
positive area and a negative area that we need to add together.
This is the same as
We'll be using the "Area" tool so bring that window up.
Graph the curve y = 2.5  x in the "Area" tool.
This time we'll use a triangle as our geometric shape.
And we'll need to do 2 calculations:
 One to calculate the positive area which is from
x = 0 to x = 2.5, and
 another to calculate the negative area which is from
x = 2.5 to x = 5.
Then we'll account for the negative area by subtracting the area we got for
x = 2.5 to x = 5 from the area we got
for x = 0 to x = 2.5.
The steps are:
 Drop a triangle down, resize it to fit between the curve and
the xaxis from
x = 0 to x = 2.5,
and then calculate (and record) this area.
Call this area A_{1}.
 Now drag and resize the triangle to fit the area between the
xaxis and the line from
x = 2.5 to x = 5,
and then calculate (and record) this area.
Call this area A_{2}.
Then the area under the line from
x = 0 to x = 5
is A_{1}  A_{2}.
Your answer for A_{1}  A_{2} should be very close to
0 since we know that
Next: Follow the "A Curve" link.
