How does the third line follow from the second in the following derivation?
$$ \sigma^2 = E[(X-\mu)^2] = E[X^2-2\mu X + \mu^2] \\ = E(X^2)-2\mu E(X)+\mu^2 \\ = E(X^2)-\mu^2 $$
2026-04-01 15:40:32.1775058032
Alternate computation for variance derivation
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