MathematicsMatrices and determinantsJAMB
Find the inverse of the matrix [[2, 1], [1, 1]].
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Answer: C. [[1, −1], [−1, 2]]
The determinant is 2 − 1 = 1; swap the diagonal entries and change the signs of the others: [[1, −1], [−1, 2]].
An AdmitMe practice question, written for the JAMB syllabus. Not an official past question.