Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Determinants

Question:

If \(A=\begin{bmatrix}1 & -1 & 1\\1 & -2 & -2\\2 & 1 & 3\end{bmatrix}\) and square matrix B satisfy AB = 8I, then the value of |B| is:

Options:

512

64

32

8

Correct Answer:

64

Explanation:

\(A=\begin{vmatrix}1 & -1 & 1\\1 & -2 & -2\\2 & 1 & 3\end{vmatrix}\)

$|A|=1(-4)+1(7)+1(5)$

$=8$

$AB=8I$

$|AB|=|8I|$

$⇒|B|=\frac{8^3}{8}=\frac{8×8×8}{8}=64$