I keep getting “Matrix as a system solver” questions wrong in Matrices & Determinants. What's the trap?
trying to 'divide' by a matrix instead of multiplying by its inverse.
The usual trap: trying to 'divide' by a matrix instead of multiplying by its inverse. How to avoid it: there's no matrix division — multiply by the inverse A⁻¹. Go back to the definition — a system of linear equations can be written as AX = B, and if A is invertible the unique solution is X = A⁻¹B.
Key point
Matrix as a system solver
Common mistake
trying to 'divide' by a matrix instead of multiplying by its inverse.
Memory tip
there's no matrix division — multiply by the inverse A⁻¹.
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