HP 39g+ - Manual (Page 161)

Using mathematical functions 11-17
Symbolic functions
The symbolic functions are used for symbolic
manipulations of expressions. The variables can be
formal or numeric, but the result is usually in symbolic
form (not a number). You will find the symbols for the
symbolic functions = and | (where) in the CHARS menu
(
CHARS ) as well as the MATH menu.
= ( equals ) Sets an equality for an equation. This is not a logical
operator and does not store values. (See “Test functions”
on page 11-18.)
expression1=expression2
ISOLATE Isolates the first occurrence of variable in expression=0
and returns a new expression, where
variable=newexpression. The result is a general solution
that represents multiple solutions by including the (formal)
variables S1 to represent any sign and n1 to represent
any integer.
ISOLATE( expression, variable)
Examples
ISOLATE(2*X+8,X) returns -4
ISOLATE(A+B*X/C,X) returns -(A*C/B)
LINEAR? Tests whether expression is linear for the specified
variable. Returns 0 (false) or 1 (true).
LINEAR?( expression, variable)
Example
LINEAR?((X^2-1)/(X+1),X) returns 0
QUAD Solves quadratic expression=0 for variable and returns
a new expression, where variable=newexpression. The
result is a general solution that represents both positive
and negative solutions by including the formal variable
S1 to represent any sign: + or – .
QUAD( expression, variable)
Example
QUAD((X -1) 2
-7,X) returns
(2+s1*5.29150262213)/2