Матричный метод Систему вида (1) можно представить в виде , где - вектор свободных членов и вектор неизвестных с вещественными координатами - , а - вещественная n ×n - матрица коэффициентов данной системы.
Тогда, умножая обе части этого векторного уравнения слева на обратную матрицу A-1 , получаем x=A-1b.
Матрица называется обратной по отношению к матрице , если при умножении этой матрицы на данную как справа, так и слева получается единичная матрица
![](data:image/png;base64,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)
Из определения следует, что только квадратная матрица имеет обратную.
Справедлива теорема, утверждающая, что обратная матрица существует (и единственна) тогда и только тогда, когда исходная матрица невырожденная.
Если матрица А системы линейных уравнений невырожденная, т.е. , то матрица А имеет обратную, и решение системы (1) совпадает с вектором C = A-1B. Иначе говоря, данная система имеет единственное решение. Отыскание решения системы по формуле X=C, C=A-1B называют матричным способом решения системы, или решением по методу обратной матрицы.
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