Schrödinger's cat

√x² = ±x
that is to say, +x AND -x coexist.
not +x OR -x exists.

as a non-mathematician,  I have been troubled by the so-called paradox of the Schrödinger's cat which is both alive and dead.  I always think that something cannot be +x and -x at the same time; it's not logical, until I thought of the above equation.

...

"Schrödinger's cat: a cat, a flask of poison, and a radioactive source are placed in a sealed box. If an internal monitor (e.g. Geiger counter) detects radioactivity (i.e. a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. The Copenhagen interpretation of quantum mechanics implies that after a while, the cat is simultaneously alive and dead. Yet, when one looks in the box, one sees the cat either alive or dead not both alive and dead. This poses the question of when exactly quantum superposition ends and reality collapses into one possibility or the other."