# Symbolic Solutions; Finding The Zeros Of A Quadratic Expression - HP -28S Manual

9
Symbolic Solutions
This chapter describes two methods for finding symbolic solutions.
There is a simple method for solving a quadratic expression by cal-
culating the linear expression that represents both zeros. There is also
a more versatile method that provides a symbolic solution for a vari-
able in more general equations.
Each method works with both expressions and equations. The
zero
of
an expression
f(x)
is the same as the
root
of the equation
f(x)
=
0, and
the
root
of the equation
f(x)
=
g(x)
is the same as the
zero
of the
expression
f(x) - g(x).
Finding the Zeros of a Quadratic Expression
You can find both zeros of a quadratic expression without plotting or
making estimates. The following example solves x
2 -
6x
+
8.
Before starting the example, clear the stack and select STD number
display mode .
1
CLEAR
I
1
3
:
I
.1
MODE
I
Put the expression on the stack.
~
X
.~
2
B
6
0
X
G
8
I
ENTER
I
9: Symbolic Solutions
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