Question Video: Finding an Element of a given Matrix

Given that matrix 𝐴 = −2, 4, −7 and −1, 9, 9, matrix 𝐵 = −7, 3, 2 and −6, −4, −8 and 7, 3, 0, and matrix 𝐶 = 2 and −5 and −4, find 𝑎₂₃, 𝑏₂₁ and 𝑐₂₁.

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Video Transcript

Given that the matrices 𝐴, 𝐵, and 𝐶 are as specified on screen, find the elements 𝑎 two three, 𝑏 two one, and 𝑐 two one.

The notation 𝑎 subscript 𝑚 subscript 𝑛 refers to the element of the matrix 𝐴 that is in row 𝑚 and column 𝑛. 𝑎 two three is therefore the element in the second row and third column of the matrix 𝐴. The number in this position is nine.

𝑏 two one is the element in the second row and first column of the matrix 𝐵. The number in this position in the matrix 𝐵 is negative six.

Finally, we consider 𝑐 two one. This is the element in the second row and first column of the matrix 𝐶. The number in this position is negative five. The element 𝑎 two three is nine. The element 𝑏 two one is negative six. And the element 𝑐 two one is negative five.

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