btw: the previous output is _, you can write solve(_,x) on your line. And another calculation could look like this, in other word, we have in fact to solve quadratic equation.
sage: d = sqrt(x^2 + 5^2) sage: D = sqrt((20-x)^2 + 10^2) sage: T = d + D; T sqrt(x^2 + 25) + sqrt((x - 20)^2 + 100) sage: der=diff(T, x); der (x - 20)/sqrt((x - 20)^2 + 100) + x/sqrt(x^2 + 25) sage: eq=der.operands()[0]==-der.operands()[1]; eq=eq^2; eq; (x - 20)^2/((x - 20)^2 + 100) == x^2/(x^2 + 25) sage: eq=eq*eq.rhs().denominator(); eq=eq*eq.lhs().denominator(); eq (x - 20)^2*(x^2 + 25) == ((x - 20)^2 + 100)*x^2 sage: eq=expand(eq); eq x^4 - 40*x^3 + 425*x^2 - 1000*x + 10000 == x^4 - 40*x^3 + 500*x^2 sage: eq=eq.lhs()-eq.rhs(); eq -75*x^2 - 1000*x + 10000 sage: solve(_,x) [x == -20, x == (20/3)] sage: der(x=-20) -8/17*sqrt(17) sage: der(x=20/3) 0 R. On 6 dub, 19:03, "ma...@mendelu.cz" <ma...@mendelu.cz> wrote: > Hi > > sage: solve((x - 20)/sqrt((x - 20)^2 + 100) + x/sqrt(x^2 + 25) == 0, > x, to_poly_solve=True) > [x == (20/3)] > > Robert M. > > On 6 dub, 15:09, Danread5 <danre...@me.com> wrote: > > > Hi all, > > > My first post... > > > I seem to be having trouble with solving for x in the following: > > > sage: d = sqrt(x^2 + 5^2) > > sage: D = sqrt((20-x)^2 + 10^2) > > sage: T = d + D; T > > sqrt(x^2 + 25) + sqrt((x - 20)^2 + 100) > > sage: diff(T, x) > > (x - 20)/sqrt((x - 20)^2 + 100) + x/sqrt(x^2 + 25) > > sage: solve((x - 20)/sqrt((x - 20)^2 + 100) + x/sqrt(x^2 + 25) == 0, > > x) > > [x == 20*sqrt(x^2 + 25)/(sqrt(x^2 + 25) + sqrt(x^2 - 40*x + 500))] > > > For some reason, Sage isn't solving completely for x, or isn't > > 'seeing' the x^2... > > > Any help gladly appreciated! > > > Dan > > -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using "remove me" as the subject.
