(a − b)³ = a³ − 3a²b + 3ab² − b³
a = longer
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b = shorter
•
(a−b) = inner side
📐 Derivation of (a−b)³
We know a³ = volume of the big cube with side a.
We cut it into 8 pieces. So:
a³ = (a−b)³ + b³ + (a−b)²b + (a−b)²b + (a−b)²b + (a−b)b² + (a−b)b² + (a−b)b²
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