Anyone knows the proof of this formula?
14764
Explain why $E(X) = \int_0^\infty (1-F_X (t)) \, dt$ for every nonnegative random variable $X$
8207
Can I prove this inequality algebraically?
91684
Prove the following equation(much needed help):
31027
Ahlfors "Prove the formula of Gauss"
144713
Simple Calculus Proof
18158
Inductive Proof for Vandermonde's Identity?
157601
Proof a formula of the Fibonacci sequence with induction
114411
Simple Proof of the Euler Identity $\exp{i\theta}=\cos{\theta}+i\sin{\theta}$
1966
Stirling's formula: proof?
8311
Is there another proof for Euler–Mascheroni Constant?
147886
Proof of the angle sum identity for $\sin$
140249
Euler Product formula for Riemann zeta function proof
85992
how to prove the chain rule?
58526
Proving Legendre's Formula
89175
Proof of $(a+b)^{n+1}$
50804
It seems obvious, but how to prove it formally?
145466
Is this a valid mathematical proof?