Equation 19 needed "substitute" not "simplify"
The chap should consider assigning the equations
as well as merely giving boolean conditionals.
With the assignment approach the worksheet (and
algebra system) can do its own parsing and reach
all the way back.
The assignment can be of the form
Eqn1 := A==B
so that one can later "solve Eqn1"
The other 'trick' is to use the math-styles to
allow the same 'variable' (e.g. "A") to have two
different, accessible, instances so one can use
both the old_A and new_A in the symbolic
substitutions.
I have done this when I needed both a forward and
reverse pass over a set of equations (Initial
values predict final values, then solve for
initial values given final values...)
Finally, normally one would place the Input
Variable page at the beginning, then add the
"undefine step" which is
variable := variable
[the symbolic processor stops when it sees such
recursion, the numeric processor still calculates.
This allows both the numeric AND symbolic
processes to act at the same time. You get both
the symbolic solution and the numeric together!
However, If you do need to clearly explain every
step to the student then often the symbolic
processor just gets in the way - It solves too
quickly 😉 [wink]
Philip Oakley
