What's wrong with this fake proof that $2+2=5$?
137970
$2 + 2 = 5$ (Fake proof, or ?)
109532
Proving $5^n \equiv 1 \pmod {2^r}$ when $n=2^{r-2}$
119109
Integer solutions to $ n^2 + 1 = 2 \times 5^m$
70522
$y^2 = \frac{x^5 - 1}{x-1}$ & $x,y \in \mathbb{Z}$
85272
$3x + 1$ is even iff $5x-2$ is odd
17491
Proof by Induction: Solving $1+3+5+\cdots+(2n-1)$
68480
Proof by Induction: Prove that $2^n > n^2$, for all natural numbers greater than or equal to $5$
102306
Why is this simple calculation of two doubles inaccurate?
143689
Real $2\times 2$ matrix $X$ such that $X^2 + 2X= -5I$
108873
How would one be able to prove mathematically that $1+1 = 2$?
2932
How do I prove this sum is not an integer
55077
prove that $2\sqrt5 +\sqrt{11}$ is irrational
63505
Proving that $ 2 $ is the only real solution of $ 3^x+4^x=5^x $
2269
Proof that the real numbers are countable: Help with why this is wrong
122083
Prove that $\sqrt[3]{2} +\sqrt{5}$ is algebraic over $\mathbb Q$
56934
How do we prove $\cos(\pi/5) - \cos(2\pi/5) = 0.5$ ?.
16172
My proof of $I \otimes N \cong IN$ is clearly wrong, but where have I gone wrong?