Replacing "x" is not right!

[DrD]

(07-23-2017 01:57 AM)Spybot Wrote:  Hello roadrunner!
That's what I'm talking about, the Prime CAS takes "x" as a zero, but I haven't assigned any numeric value to it.

My thoughts on this topic:

x^4-2*x^3+5|x = x; // where x is not sign changed ==> 5
plotfunc((x^4-2*x^3+5|x = -x); // Suggests a result of 5 (no labels)
plotfunc((x^4-2*x^3+5|x = x); // As above...

These expressions validate that x is assumed to have a value of zero, and thus is not symbolic. However, if:

(r^4-2*r^3+5|(r = (-x))); // ==> (-x)^4-2*(-x)^3+5 the variable x remains symbolic.

Is the original expression sufficiently well described, or is the expression a matter of interpretation, where both Spybot, and Road, have correct solutions? In short, perhaps the provided result IS right, but the expression itself needs better formulation?

Dale