What is wrong with the following proof that tries to prove that $2=1$?
39908
Finding the error in this proof that 1=2
70311
Trying to prove (A ∩ B) − C = (A − C) ∩ (B − C)
92595
A problem regarding the in-equality of complex numbers .
38404
Prove $\gcd(a+b, a-b) = 1$ or $2\,$ if $\,\gcd(a,b) = 1$
56169
What mistakes, if any, were made in Numberphile's proof that $1+2+3+\cdots=-1/12$?
38995
Induction proof that $\sum_{j=n}^{2n-1} (2j + 1) = 3n^2$ - what happened?
147528
Where's the error in this $2=1$ fake proof?
86567
Understanding $\sum_{x = 0}^y x = \frac{y(y + 1)}{2}$ in a step of a proof
40532
Seems that I just proved $2=4$.
79274
$1=2$ | Continued fraction fallacy
141496
Could someone make the proof into a hinted exercise?
105164
If $abc=1$, prove that $\frac{2}{(a+1)^2+b^2+1} + \frac{2}{(b+1)^2+c^2+1} + \frac{2}{(c+1)^2+a^2+1} \le 1$.
32524
Flawed proof that all positive integers are equal
33402
What is wrong with this funny proof that 2 = 4 using infinite exponentiation?
77026
Proof with inequalities
65511
Proving the following false: $f(x)=2x+1$ produces a prime number if and only if x is prime
154133
Flawed proof by induction that $a^{n-1}=1$