Solve: We can't request symbol when it depends of more than 1 eq and syms != system syms

[latot]

Hi, basically the title, if we request symbols if it depends of more than 1 eq and when symbols request don't are the full symbols in the system, and the system don't is solved:

>>> solve([Eq(x+y,1), Eq(x-y,1)], x)
[]
>>> solve([Eq(x,1), Eq(x+y,1)], x)
[]
>>> solve([x+y+z, x+y-z], x, y)
[]
This works (when only depend of one eq) (the system don't is simplified):
>>> solve([Eq(y,1), Eq(x+y,1)], x)
{x: -y + 1}

Thx. Cya.

[Shekharrajak]

Since it is a liner system so it should be solvable using linsolve, but there is already known bug:

In [35]: linsolve([x+y+z, x+y-z], [x, y])
Out[35]: ∅

You can use substitution method :

In [36]: substitution([x+y+z, x+y-z], [x, y])
Out[36]: {(-y - z, y)}

[latot]

This are only examples, this happen with non linear equations too:

>>> solve([Eq(x**2+y,1), Eq(x-y**2,1)], x)
[]