1. ## Proving variance formula

How does one prove the formula: var(X) = E(X2) − E2(X)?

Thanks!

2. $\displaystyle V(X) = E(X-\mu)^2 = E(X^2 - 2 \mu X + \mu^2)$

$= E(X^2) - 2 \mu E(X) + E(\mu^{2})$

$= E(X^2) - 2 \mu^{2} + \mu^{2} = E(X^2) - \mu^{2}$

### proving statistics formula

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