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Applied Mathematics · Ch 2 — Algebra

Finding Inverse Matrix by Inverse of Coefficient Matrix Method

2.7.2

Finding Inverse Matrix by Inverse of Coefficient Matrix Method

Recall that for any square matrix AA of order nn, the adjoint satisfies A(adj A)=(adj A)A=∣A∣ IA(\text{adj}\,A) = (\text{adj}\,A)A = |A|\,I. Dividing through by ∣A∣|A|, whenever that's possible, immediately gives a ready-made formula for the inverse:

A−1=1∣A∣ adj AA^{-1} = \dfrac{1}{|A|}\,\text{adj}\,A …