HP 39g+, User Manual

Page: 167 / 294

Using mathematical functions 11-23
To find the
indefinite integral
using formal
variables
For example, to find the indefinite integral of
use:
1. Enter the function.
0
S1 3
X 5
X
2. Show the result format.
3. Press to close the
show window.
4. Copy the result and
evaluate.
Thus, substituting X for S1, it can be seen that:
This result is derived 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:
3 x
2
5 – x d
∫
( )
∫
−
X X S , 5 3 , 1 , 0
2
hp 39g
+
3 x
2
5 – x 5 x – 3
x
3
3
-----
X
∂
∂
X
( )
---------------
 
 
 
 
 
+ = d
∫
x 2 –
( )
4
x
x
(
2
)
5
–
5
-------------------
= d
∫