If A is an invertible matrix of order 2, then det (A−1) is equal to ______.

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If A is an invertible matrix of order 2, then det (A−1) is equal to underline(1/det (A)). Explanation: because A invertible matrix => abs "A" ne 0 therefore "AA"^-1 = "I" and abs ("AA"^-1) = abs "I" = 1 => abs "A" abs ("A"^-1) = 1 => abs ("A"^-1) = 1/abs "A" => det ("A"^-1) = 1/det("A")

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