For Δ = det[1, 3, -2; 4, 0, 5; 2, -1, 6], what is the cofactor A₃₂?

Determinants, Adjoint & Inverse · Question 44 of 87

Question 44

MediumOriginal question

For $\Delta = \begin{vmatrix}1 & 3 & -2 \\ 4 & 0 & 5 \\ 2 & -1 & 6\end{vmatrix}$ , what is the cofactor $A_{32}$ ?

-13

Correct answerYour answer

-12

Correct answerYour answer

13

Correct answerYour answer

15

Correct answerYour answer

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CorrectNot quiteAnswer A

Correct answer: A

Delete row 3 and column 2: the minor is $\begin{vmatrix} 1 & -2 \\ 4 & 5 \end{vmatrix} = 5 + 8 = 13$ .
$A_{32} = (-1)^{3 + 2} \times 13 = -13$ .

Worth noting

13 is the minor; the cofactor carries the sign $(-1)^{i + j}$ .

Ten questions from Determinants, Adjoint & Inverse, at your own pace.

Ten questions from Determinants, Adjoint & Inverse, at your own pace.