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Matrices · Question 69 of 106

Question 69

MediumOriginal question

If A=[01−10]A = \begin{bmatrix}0 & 1 \\ -1 & 0\end{bmatrix}, what is A6A^{6}?

Options for question 69

Show the answer and explanation
CorrectNot quiteAnswer B

Correct answer: B

Explanation

  1. A2=[−100−1]=−IA^{2} = \begin{bmatrix} -1 & 0 \\ 0 & -1 \end{bmatrix} = -I.

  2. A6=(A2)3=(−I)3=−IA^{6} = (A^{2})^{3} = (-I)^{3} = -I.

Worth noting

II is A4A^{4}; one more A2=−IA^{2} = -I turns it to −I-I.

Concept
Powers of a matrix
Typical time
90 s
Your time
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The rule this testsProperties of multiplication, and powers
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Ten questions from Matrices, at your own pace.

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Ten questions from Matrices, at your own pace.