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det(\left(\begin{matrix}-3&0&5\\3&4&-4\\-5&4&-6\end{matrix}\right))
Find the determinant of the matrix using the method of diagonals.
\left(\begin{matrix}-3&0&5&-3&0\\3&4&-4&3&4\\-5&4&-6&-5&4\end{matrix}\right)
Extend the original matrix by repeating the first two columns as the fourth and fifth columns.
-3\times 4\left(-6\right)+5\times 3\times 4=132
Starting at the upper left entry, multiply down along the diagonals, and add the resulting products.
-5\times 4\times 5+4\left(-4\right)\left(-3\right)=-52
Starting at the lower left entry, multiply up along the diagonals, and add the resulting products.
132-\left(-52\right)
Subtract the sum of the upward diagonal products from the sum of the downward diagonal products.
184
Subtract -52 from 132.
det(\left(\begin{matrix}-3&0&5\\3&4&-4\\-5&4&-6\end{matrix}\right))
Find the determinant of the matrix using the method of expansion by minors (also known as expansion by cofactors).
-3det(\left(\begin{matrix}4&-4\\4&-6\end{matrix}\right))+5det(\left(\begin{matrix}3&4\\-5&4\end{matrix}\right))
To expand by minors, multiply each element of the first row by its minor, which is the determinant of the 2\times 2 matrix created by deleting the row and column containing that element, then multiply by the element's position sign.
-3\left(4\left(-6\right)-4\left(-4\right)\right)+5\left(3\times 4-\left(-5\times 4\right)\right)
For the 2\times 2 matrix \left(\begin{matrix}a&b\\c&d\end{matrix}\right), the determinant is ad-bc.
-3\left(-8\right)+5\times 32
Simplify.
184
Add the terms to obtain the final result.