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From the documentation for solve: If any equation does not depend on the symbol(s) given, it will be eliminated from the equation set and an answer may be given implicitly in terms of variab...
#1: Initial revision
by
r~~
·
2026-07-07T07:49:15Z (2 months ago)
From [the documentation for `solve`](https://docs.sympy.org/latest/modules/solvers/solvers.html#sympy.solvers.solvers.solve):
> * If any equation does not depend on the symbol(s) given, it will be eliminated from the equation set and an answer may be given implicitly in terms of variables that were not of interest:
>
> ```python
> >>> solve([x - y, y - 3], x)
> {x: y}
> ```
That's what you're encountering here, as your `eq2` doesn't depend on `a`.
Simplest thing is to omit the symbol altogether:
```python
>>> sp.solve([eq1, eq2])
[{a: 4, x1: -sqrt(-x2**2 - x3**2 + 1)}, {a: 4, x1: sqrt(-x2**2 - x3**2 + 1)}]
```
Unfortunately, this requires a bit of extra interpretation to see that the value found for `a` is the same in both solutions. I think that's just something to live with.