What is wrong with this proof that x = |x|
59818
Why $(-2)^{2.5}$ isn't equal to $((-2)^{25})^{1/10}$?
41182
What does the construct x = x || y mean?
89637
Proof that in a field $x=0$ is equivalent to $x=-x$
14161
Proof of when is $A=X^TX$ invertible?
62172
Why does $-b < a < b \iff |a| < b$?
155579
Show that $End_A(A)$ = {$r_a$ | $a ∈ A$}
98271
Why does $(x \to a) ≠ (x = a)$ , But $f(x \to a) = f(x = a)$
82739
Why is $\alpha \rightarrow \forall x(\alpha)$ not generally correct in first-order logic?
27888
Why is $|x|$ not differentiable at $x=0$?
135694
Proving $\kappa^{\lambda} = |\{X: X \subseteq \kappa, |X|=\lambda\}|$
27782
Why does this proof of the chain rule not work?
31954
Why this proof $0=1$ is wrong?(breakfast joke)
118949
If $(Tx \mathbin{|} x) = 0$ for all $x$ then $T = 0$
3820
Prove that $||x|-|y||\le |x-y|$
51877
Why is this 'Proof' by induction not valid?
36954
What does the construct f[x_] := f[x] = ... mean?
145397
How to prove that for every $i$, $a_i = i$