📐 Linear Algebra · Chapter 4-6
Inverse Matrices & Systems
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⚡ Quick Memory Points
IDENTITY (I)
Main diagonal = 1, all others = 0.
A · I = I · A = A
INVERSE CHECK
A · A⁻¹ = A⁻¹ · A = I
Both orders MUST equal I
2×2 INVERSE
If A=[a b; c d], then
A⁻¹ = 1/(ad-bc) · [d -b; -c a]
DETERMINANT
det(A) = ad - bc
If det = 0 → NO inverse!
Quiz Complete! 🎉