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Determinant of a 2x2 matrix

Sal shows how to find the determinant of a 2x2 matrix. Created by Sal Khan.

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Video transcript

As a hint, I'll take the determinant of a very similar two by two matrix. So we wanna figure out the determinant of this matrix and we can denote it by the determinant of the 2x2 matrix five, three,negative one and four and the definition of determinant of the 2x2 matrix like this, as we can first take this diagonal, five times four so write it down, just going to be equal to 5 * 4 minus of product of that diagonal ...so what is this give us? So, five times four is twenty and then three times negative one will be negative three this is negative three... but making negative the negative three will make the positive three so the determinant of this matrix is twenty three.