Lesson 28: areas under curves, Z 0 0 m (nxt) (nxt~), A l i – HP 48G User Manual
Page 83: I i . . . . / . . i
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Lesson 28: Areas Under Curves
The FiN:EFi command in the PICTURE FCN menu hnds a definite
integral based
on
the current function.
That
is, it calculates
and
displays the area lietween the current function and the x-axis between
two
X-values
you designate.
Example:
Find the area under the current polynomial
(A'® + A"^ — 5A'® — 2A''- + A 4) between
, r
= —2.2 and
,r = —1..0.
S t e p 1 :
Reopen PLOT and redraw’ the polynomial.
®
(B©
3
0
(
enter
)3
(
enter
)(Q
12
(V-) (
enter
)
12
(ENTER)
i
\ . I I . . . . / . .
i
_3
S t e p 2 :
Use Decimal
Zoom
to
force each
horizontal
pixel to
be
equivalent to 0.1 units. Then move the cursor to .r = —2.2
(the lower limit),
and
mark
it.
Note
the use
of
the
mu It i p 1 i c a t i o n ke y
to “mark” a cursor position.
Z 0 0 M (NXT) (NXT~)
F'i a 'T )
© or a as needed
(x) (to mark the cursor position)
. . . A l
I
fc
-iJ
V: -1.30H76E-1
S t e p S :
Find
the selected
area.
Note that for
finding the
numerical
integral, the
shading is
for display
purposes
only and is
entirely optional.
©(
I
times)
(NXT) (to redisplay the menu)
, , , a l
I
I
HREH: S.B0ds091ESl
■ > /
Plotting Equations and Analyzing Graphs 6-17