Is there a way for the solve app to use exact figures?

[Stevetuc]

(10-22-2020 04:36 PM)Albert Chan Wrote:  

(10-22-2020 04:11 AM)Stevetuc Wrote:  exact(proot([1,-1,6^2+31^2]))

2 issues:
1). you missed the +6 for the constant term.
2). approximate solutions, then apply exact, does not give exact solutions.
(some cases do work, if exact solutions are "simple" rational; but not in general)

BTW, exact is a bad name. It really meant float2rational (conversion likely *not* exact)

I don't have HP Prime, but in XCas, you can use solve (with complex ON)

XCas> eqn := subst(a^2+b^2+c^2+6-a, [b,c]=[6,31])       → a^2-a+1003
XCas> solve(eqn=0, a)       → \([{1+i\sqrt{4011} \over 2}, {1-i\sqrt{4011} \over 2}]\)

Thanks Albert, I learnt something!