
286
F
F
i
i
n
n
d
d
i
i
n
n
g
g
c
c
r
r
i
i
t
t
i
i
c
c
a
a
l
l
p
p
o
o
i
i
n
n
t
t
s
s
a
a
n
n
d
d
g
g
r
r
a
a
p
p
h
h
i
i
n
n
g
g
a
a
p
p
o
o
l
l
y
y
n
n
o
o
m
m
i
i
a
a
l
l
For the function
3
2
( )
4
6
f x
x
x
x
=
−
+ +
…
(i)
find
the
intercepts.
(ii)
find the turning points.
(iii)
draw a sketch graph showing this information.
(iv)
find the area under the curve between the two turning points.
Step 1. Enter the function into the
SYMB
view
of the Function aplet, so it is available
for plotting.
Step 2. Use the
POLYROOT
function to find the
roots. This function is in the
MATH
menu in the
Polynom.
group.
The results show that the x intercepts
are
( 1, 0), (2, 0)
−
and
(3, 0)
. The y
intercept is found by evaluating
F1(0)
in the
HOME
view giving the point (0,6).
Step 3. Switching to the
PLOT
view via
VIEWS
-
Decimal
, you will find that the
function does not display as well as it
could. Since it is the y axis that is not
displaying enough, we will use the ‘
Y-
Zoom Out
’ option in the
menu
after first setting the
Zoom factors
to 2 rather than 4 (which is too drastic).
Now use the
pop-up menu to find
the
Extremum
(both left and right).
The snapshot right shows the left-hand turning point of (0.131,6.065).