HP 39g+ User Manual
Page 161
Using mathematical functions
10-25
To find the
indefinite integral
using formal
variables
For example, to find the indefinite integral of
use:
1. Enter the function.
>6+,)7@>GG[@0>@
>$/3+$@S1 >@ 3 >[@
>$/3+$@X >[@ >@ 5 >@
>$/3+$@X >@ >(17(5@
H I N T
If the Decimal Mark setting in the Modes input form
(
>6+,)7@
MODES
)is set to Comma, use
>@ instead of >@.
2. Show the result format.
*k,
TCPX
3. Press
PF
to close the
show window.
4. Copy the result and evaluate.
8PQ`Ã
>(17(5@
Thus, substituting X for S1, it can be seen that:
This result derives from substituting X=S1 and X=0 into the
original expression found in step 1. However, substituting
X=0 will not always evaluate to zero and may result in an
unwanted constant.
To see this, consider:
3x
2
5
–
x
d
∫
0 S1 3X
2
,
5 X
,
–
,
(
)
∫
HP 39G
HP 40G
3x
2
5
–
x
5x
–
3
x
3
3
-----
X
∂
∂
X
( )
---------------
+
=
d
∫
x
2
–
(
)
4
x
x
(
2
)
5
–
5
-------------------
=
d
∫