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det(\left(\begin{matrix}4&-2&3\\1&0&2\\-1&4&5\end{matrix}\right))
Find the determinant of the matrix using the method of diagonals.
\left(\begin{matrix}4&-2&3&4&-2\\1&0&2&1&0\\-1&4&5&-1&4\end{matrix}\right)
Extend the original matrix by repeating the first two columns as the fourth and fifth columns.
-2\times 2\left(-1\right)+3\times 4=16
Starting at the upper left entry, multiply down along the diagonals, and add the resulting products.
4\times 2\times 4+5\left(-2\right)=22
Starting at the lower left entry, multiply up along the diagonals, and add the resulting products.
16-22
Subtract the sum of the upward diagonal products from the sum of the downward diagonal products.
-6
Subtract 22 from 16.
det(\left(\begin{matrix}4&-2&3\\1&0&2\\-1&4&5\end{matrix}\right))
Find the determinant of the matrix using the method of expansion by minors (also known as expansion by cofactors).
4det(\left(\begin{matrix}0&2\\4&5\end{matrix}\right))-\left(-2det(\left(\begin{matrix}1&2\\-1&5\end{matrix}\right))\right)+3det(\left(\begin{matrix}1&0\\-1&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.
4\left(-4\times 2\right)-\left(-2\left(5-\left(-2\right)\right)\right)+3\times 4
For the 2\times 2 matrix \left(\begin{matrix}a&b\\c&d\end{matrix}\right), the determinant is ad-bc.
4\left(-8\right)-\left(-2\times 7\right)+3\times 4
Simplify.
-6
Add the terms to obtain the final result.