This is a classical mathematical fallacies. At hindsight, everything looks perfectly fine.

This is a rather difficult one as the error is actually hidden in the second last line! The mistake here is that we conveniently removed the power, but overlooked that there will be a $\pm{ }$. If we do account for it, we will have the original result.

### One Comment

• […] Classical Mathematical Fallacies #2 […]