WEBVTT
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Find the determinant of the following matrix five, one, negative one, five.
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We recall that the determinant of any matrix is written inside absolute value bars.
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The determinant of the two-by-two matrix 𝑎, 𝑏, 𝑐, 𝑑 is equal to 𝑎𝑑 minus 𝑏𝑐.
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The determinant of the matrix five, one, negative one, five is equal to five multiplied by five minus one multiplied by negative one.
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Five multiplied by five is equal to 25.
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Multiplying a positive number by a negative number gives a negative answer.
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Therefore, one multiplied by negative one is negative one.
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We know that subtracting negative one is the same as adding one.
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The determinant of the matrix five, one, negative one, five is therefore equal to 26.