Back to Determinants

Exercise 5

Avg difficulty 2.5

Determine whether the following statements are true or false and explain your response.

  1. If we have a square matrix AA and multiply the first row by 55 and add it to the third row to obtain A′A', then det⁡(A′)=5det⁡(A)\det(A') = 5\det(A).

  2. If we interchange two rows of a matrix, then the determinant is unchanged.

  3. If we scale a row of the matrix AA by 1717 to obtain A′A', then det⁡(A′)=17det⁡(A)\det(A') = 17\det(A).

  4. If AA and A′A' are row equivalent and det⁡(A′)=0\det(A') = 0, then det⁡(A)=0\det(A) = 0 also.

  5. If AA is row equivalent to the identity matrix, then det⁡(A)=det⁡(I)=1\det(A) = \det(I) = 1.

Austin, Understanding Linear Algebra, §3.4 Determinants, Exercise 5

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Adapted from Understanding Linear Algebra © 2023 David Austin. Licensed under CC BY 4.0. Source: Understanding Linear Algebra. Imported at revision 3e6dced.