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Linear AlgebraMediumDeterminants & Inverses

Determinants & Inverses · Medium problem

A budget tracker records quarterly amounts for three expense categories as the rows of M=(235112459)M=\begin{pmatrix}2&3&5\\1&1&2\\4&5&9\end{pmatrix}. An auditor suspects category CC's row is fully explained as a combination of categories AA and BB (so det⁡M=0\det M=0, confirmed). The Q3 entry for category CC (currently 99) was recorded sloppily; find the smallest positive integer amount by which it must be increased for the three categories to stop being redundant (i.e. for det⁡M\det M to become nonzero).