substitute [<var> [using <equation#>]]

The "substitute" command is used to solve simultaneous equations using the method of substitution.  The specified equation is solved in terms of the variable, and the resulting right-hand-side is used to replace all occurrences of the variable in other equations.

If no equation number is specified, the program automatically chooses an equation containing the variable.

If neither parameter is specified, the program examines the simultaneous equations and their unknowns to choose a variable and corresponding equation for substitution.  Substitution only occurs if the system can be simplified.

e.g.   x+2y=5                 Enter simultaneous equation #1.
3x=11+y Enter simultaneous equation #2.

e.g. substitute Try an automatic substitution.
e.g. substitute x Force a substitution of "x".
e.g. substitute x using 1 Forced "x" substitution using "x=5-2y".
See also:  info, eliminate