HP -22S Owner's Manual page 169

Example: Using Good Guesses To Find a Solution. Find the root
of the equation:
'Ix
+
lnx - .5
=
0
SOLVE Equation: SQRT< X +LN (X) ) -.5=13
Notice that
x
must be greater than 0 to avoid an error due to the
LN
function.
Keys: Display:
Description:
Attempt to find a positive root with guesses 1 and 5.
1
(]jQJ
X
5.'SOLVE!
'RCL!
X
LOG(NEG)
X=-0.2732
Math error.
'SOLVE!
found no root
between 1 and 5, and
tried a negative
x.
See what happens when you use very good guesses .
. 6
(]jQJ X
.7 . ,
SOLVE!
.'LAST!
((x)
i
'SOLVE
I
finds a root.
X=0.6622
-1.0000E-12
I(x)
is very small.
~
i L i
x
1
((x)
=
'Ix
+
Inx - .5
B: More About Solving Equations 169