Introduction to Quantum Mechanics · Problem A.7

Afterword — David J. Griffiths

Physics — Quantum Mechanics · inner-products

Problem

Prove the triangle inequality: ∥(∣α⟩+∣β⟩)∥≤∥α∥+∥β∥\|(|\alpha\rangle + |\beta\rangle)\| \leq \|\alpha\| + \|\beta\|.

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