A proof that $1=2$. May I know why it’s false? [duplicate]
Solution 1:
You cannot add '$x$', $x$ number of times without knowing what $x$ exactly is. Hence the differentiation on the RHS has no real meaning.
This fails for many cases like:
$1)$ '$x$' is not an integer.
$2)$ Dependency of $x$ on $x$ which you are not considering when differentiating on RHS.