What's the error in this proof?
5080
How can we sum up $\sin$ and $\cos$ series when the angles are in arithmetic progression?
63559
Is there a more complete way of proving this theorem (that I devised)? OR does this theorem already exist and have a name?
12802
Proof of correctness of normal equation
59872
How to prove $\inf(S)=-\sup(-S)$?
108923
What is wrong with this false proof? $-1=(-1)^1=(-1)^\frac{2}{2}=((-1)^2)^\frac{1}{2}=\sqrt{(-1)^2}=\sqrt{1}=1$
59280
Need help with Proof by Strong Induction question
23701
I have a problem understanding the proof of Rencontres numbers (Derangements)
143248
What approach should I take to establish this logical proof?
100399
A doubt with a part of a certain proof.
76506
What is the flaw of this proof (largest integer)?
23246
Challenge question; How do I prove the expected value of the following?
29531
A Question On Euler's Proof Of the Basel Problem
45548
An error in application of Runge's theorem
158335
Why is this $0 = 1$ proof wrong?
32524
Flawed proof that all positive integers are equal
118577
Fallacious proof involving trigonometry
89354
Polynomials, prove exercise question about question