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The inverse of the matrix A=[120001400018]A = \begin{bmatrix} \frac{1}{2} & 0 & 0 \\ 0 & \frac{1}{4} & 0 \\ 0 & 0 & \frac{1}{8} \end{bmatrix} is

Solution

✅ Correct Option: 3

Matrix AA is a diagonal matrix:

A=[120001400018]A = \begin{bmatrix} \frac{1}{2} & 0 & 0 \\ 0 & \frac{1}{4} & 0 \\ 0 & 0 & \frac{1}{8} \end{bmatrix}

All non-diagonal entries are zero, with non-zero elements only on the main diagonal.


For a diagonal matrix, the inverse is found by taking the reciprocal of each diagonal element.

112=2\frac{1}{\frac{1}{2}} = 2

114=4\frac{1}{\frac{1}{4}} = 4

118=8\frac{1}{\frac{1}{8}} = 8


The inverse matrix is:

A−1=[200040008]A^{-1} = \begin{bmatrix} 2 & 0 & 0 \\ 0 & 4 & 0 \\ 0 & 0 & 8 \end{bmatrix}

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