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Evaluate the following determinant: |[...

Evaluate the following determinant: `|[1, 4, 9],[ 4, 9, 16],[ 9 ,16, 25]|`

A

-6

B

4

C

-8

D

5

Text Solution

AI Generated Solution

The correct Answer is:
To evaluate the determinant \[ D = \begin{vmatrix} 1 & 4 & 9 \\ 4 & 9 & 16 \\ 9 & 16 & 25 \end{vmatrix} \] we will use the method of cofactor expansion along the first row. ### Step 1: Expand the determinant along the first row Using the formula for the determinant, we have: \[ D = 1 \cdot \begin{vmatrix} 9 & 16 \\ 16 & 25 \end{vmatrix} - 4 \cdot \begin{vmatrix} 4 & 16 \\ 9 & 25 \end{vmatrix} + 9 \cdot \begin{vmatrix} 4 & 9 \\ 9 & 16 \end{vmatrix} \] ### Step 2: Calculate the 2x2 determinants Now we will calculate each of the 2x2 determinants. 1. For the first determinant: \[ \begin{vmatrix} 9 & 16 \\ 16 & 25 \end{vmatrix} = (9 \cdot 25) - (16 \cdot 16) = 225 - 256 = -31 \] 2. For the second determinant: \[ \begin{vmatrix} 4 & 16 \\ 9 & 25 \end{vmatrix} = (4 \cdot 25) - (16 \cdot 9) = 100 - 144 = -44 \] 3. For the third determinant: \[ \begin{vmatrix} 4 & 9 \\ 9 & 16 \end{vmatrix} = (4 \cdot 16) - (9 \cdot 9) = 64 - 81 = -17 \] ### Step 3: Substitute back into the determinant expression Now substituting these values back into our expression for \(D\): \[ D = 1 \cdot (-31) - 4 \cdot (-44) + 9 \cdot (-17) \] Calculating each term: \[ D = -31 + 176 - 153 \] ### Step 4: Simplify the expression Now, we simplify: \[ D = -31 + 176 - 153 = -31 + 23 = -8 \] Thus, the value of the determinant is \[ \boxed{-8} \]

To evaluate the determinant \[ D = \begin{vmatrix} 1 & 4 & 9 \\ 4 & 9 & 16 \\ 9 & 16 & 25 \end{vmatrix} ...
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