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explain solution RD Sharma class 12 chapter 5 Determinants exercise Fill in the blanks question 8 maths

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Answer: \partial =\pm 3

Hint: Here, we use basic concept of determinant of matrix

Given: \left | A \right |^{3}=125,  A=\begin{bmatrix} \partial & 2\\ 2& \partial \end{bmatrix}

Solution: Here, A=\begin{bmatrix} \partial & 2\\ 2& \partial \end{bmatrix}

                So, \left | A \right |=\partial \times \partial -2\times 2

                \left | A \right |=\partial^{2} -4                            ........(1)

         And,\left | A \right |^{3}=125

                \left ( \left | A \right | \right )^{3}=125

                \left ( \left | A \right | \right )^{3}=(5)^{3}

                \left | A \right |=5                                    ...........(2)

From equation (1) and equation (2)

                \partial ^{2}-4=5

                \partial ^{2}=4+5

                \partial ^{2}=9

                \partial=\pm 3

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