HP 39G Master Guide

80
Integration: The definite integral using the
∫
function
The situation for integration is very similar to that of differentiation. The
difference is that both the HOME view and the Function aplet require the use
of a “formal variable” S1. As with differentiation, the results are better in the
Function aplet. The
∫
symbol is obtained via the keyboard.
The syntax of the integration function is:
(,, , )a b function X
∫
where: a and b are the limits of integration
and function is defined in terms of X.
Let’s look first at the definite integral…
The screen left shows
2
2
1
1
x
dx+
∫
= 3.3333…
followed by
ln2
0
x
edx
∫
= 1.
It may help you to remember the syntax of the differentiation and integration
functions if you realize that they are filled in with values in exactly the same
way that they are spoken.
E.g.
2
2
1
1
x
dx+
∫
is read as:
“the integral from 1 to 2 of
2
1x
+
dx ”
& entered:
∫
( 1, 2,
2
1X
+
, X )
A similar path was taken with the differentiation function,
so that:
2
d
X
dx


, which is read as “the derivative with respect to X of X
2
”
and entered
()
2
X
X ∂ :
∂
X
()
2
X

HP 39G Specifications

General

Brand	HP
Model	39G
Category	Calculator
Language	English