Step4.
Because I know that part (iv) of the question requires me to re
use these extremum values in an integration (which I would like
to be as accurate as possible), I am going to ‘save’ the
extremum value just found. I change into the
HOME
view and
store it as shown in memory
A
.
Note
: You MUST store the point of interest before moving the
cursor in the
PLOT
view. As soon as the cursor moves its new
position over-writes the extremum value. If you want the y
coordinate, just evaluate
F(X)
.
Extremum
tool again to find and store the
x coordinate of the second turning point into memory
B
as
shown.
Now use the
Step 5.
The
PLOT
view shows that part of the area we require for part
(iv) is negative, so we need to know the x intercept between
the two turning points. Fortunately we know from Step 2 that it
is the point (2,0). If we did not know this already, then we
could use the
menu again, retrieving this time from the
VAR
menu the variable called ‘
Root
’ and perhaps storing that
into memory
C
.
We will evaluate the integral in the
HOME
view where you
can use the accurate values you stored in Step 4. It needs to
be done in two parts and added (subtracted actually to reverse
the sign of the negative part). This is shown right, with the
key having been used to add the values.
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