ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sat, 11 Feb 2012 11:56:41 +0100Symbolic solvehttps://ask.sagemath.org/question/8707/symbolic-solve/Following the [change of variable thread](http://ask.sagemath.org/question/1113),
I wanted to streamline the whole process.
Namely, using the same example in the above thread, I'd like to say
integral_def_change(x*cos(x^2+1), (x, 0, 2*pi), u == x^2 + 1, u)
The difference is, I wanted also Sage to automatically solve for `x`
instead of providing `x = sqrt(u - 1)`, say. But when I tried
solve(u == x^2 + 1, x)[0].rhs()
the output was `r1`.
1- What exactly is r1 ??
A way out (see this [thread](http://ask.sagemath.org/question/1105))
seems to make of the solution a function of `u`
f(u) = solve(u == x^2 + 1, x)[0].rhs()
Now f is
u |--> -sqrt(u - 1)
2- What can I do to get `+sqrt(u - 1)` instead? Is this related to the
[positive function question there](http://ask.sagemath.org/question/989)?Green diodSat, 11 Feb 2012 11:56:41 +0100https://ask.sagemath.org/question/8707/