WEBVTT

1
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Here is the problem: [[1, 2], [3, 4]].

2
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Find the determinant of a 2 times 2 matrix.

3
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Read the 2 times 2 matrix.

4
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Use ad minus bc for a 2 times 2 matrix.

5
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So the answer is det(A) equals negative 2.

6
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The determinant is negative 2, which is non-zero, so the matrix is invertible and its rows are linearly independent.

7
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Computed exactly with fractions; row reduction gives the same value negative 2.