HP -22S Owner's Manual page 155

More About Solving
Equations
B
I
SOLVE
I
uses an iterative process that searches for a number that sets
the left side of the equation equal to the right side. A convenient way
to conceptualize the process is to think of the equation as a function
of one variable, the
unknown,
for which
I
SOLVE
I
is seeking a
root.
The
root of a function is a number that sets the value of the function equal
to O. For convenience, this appendix will consistently use
x
as the un-
known.
How
I
SOLVE
I
Finds a Root
Consider an equation containing a number of variables, including un-
known x. When values have been entered for all variables except the
unknown, the equation has the form:
g(x)
=
h(x)
where
g(x)
and
hex)
are the left and right sides of the equation. For
example, when the equation:
is solved for x with a=-2, b=8, r=2, c=24, and d=-8, it has the
form:
-2.x3
+
4x
2
=
6x - 8
\ T
J
\'---v-. - - '
g(x) h(x)
B: More About Solving Equations 155