Is there an inverse of `fma`

, in the sense of

```
y = fma(x, A, B)
x2 = ???(y, A, B) # this is what I am looking for
x ≈ x2 # "reasonably" close
```

I found that sometimes either `(y - B)/A`

or `fma(y, inv(A), -B/A)`

is more accurate, but it really depends on the magnitude of `B`

vs `A`

.