HP 40G manual Symbolic functions, Isolate, Linear?, Quad

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 (>6+,)7@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 10-
	20.)
	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

Using mathematical functions 10-19