# Proof without Words

by Farhood Pouryoussefi (Iran)

Mathematics Magazine
December, 1989

Subject classification(s): Patterns and Sequences
Applicable Course(s): 3.7 Discrete Math | 4.1 Introduction to Proofs

Why is $(\sum_{i=1}^n i)^2 = \sum_{i=1}^n i^3$? The authors offer both a combinatorial and geometric visual proofs.

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