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On the other hand there is a way to further

simplify the expression. If you now the

result and enclose it with the POLYFORM

function as shown right (note the final ‘,X’),

then highlight it and press , the hp 39g+

will expand the brackets and gather terms.

Calculator Tip

These functions can all be graphed but the speed of

graphing is slowed if you don’t press first. The 39G+

is fast enough that the result can be lived with but the 39G

and 40G are usually too slow when graphing un-evaluated

composite functions.

Evaluating the function may also hide the

domain. For example, if

1( )

XX= and

2( )

XX= then 3( ) 1( 2( ))

XFFX= will show

the correct domain of

0x ≥

in the NUM view.

Pressing will destroy this.

Using functions in the HOME view

Once functions have been defined in the SYMB view of the Function aplet,

they can be reused in the HOME view (and indeed in any other aplet!).

For example suppose you needed to find some exact points (x = 0, 1, 2 and

3) for a graph of

()

−

when doing a hand sketch of it.

Type its definition into the Function aplet SYMB

view, switch to the HOME view and then simply

type F1(0) and press ENTER. The function will

be evaluated for x = 0. Similar results can be

obtained for F1(1), F1(2) and F1(3). Notice the

error message for x = 2 caused by a divide by

zero.

HP 39G Master Guide

Other manuals for HP 39G