Finding Inverse of a matrix
Last updated at August 2, 2026 by Teachoo
Transcript
Ex 4.4, 17 (Method 1) Let A be a nonsingular square matrix of order 3 Ć 3. Then |adj A| is equal to A. |A| B. |A|2 C. |A|3 D. 3 |A| We know that |ššš š“| = |š“|^(š ā 1) where n is the order of Matrix A Here, n = 3 |ššš š“| = |š“|^(3 ā 1) = |š“|^2 Hence, B is the correct answer Ex 4.4, 17 (Method 2) Let A be a nonsingular square matrix of order 3 Ć 3. Then |adj A| is equal to A. |A| B. |A|2 C. |A|3 D. 3 |A| We know that A (adj A) = |A|I Taking determinants both sides |A (ad jA)| = ||A|I| Solving |A (adj (A))| |A (adj (A))| = |A| |adj (A)| Solving ||A|I| ||A|I| = |A|3|I| = |A|3 Now, |A (ad jA)| = ||A|I| Putting values |A| |adj (A)| = |A|3 |adj (A)| = |A|3/|A| |adj (A)| = |A|2 Thus, B is the correct answer