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# Matrices Question MEI

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1. How do I go about this? The mark scheme on the MEI website confused me.

Thanks,
Sora
2. (Original post by Sora)

How do I go about this? The mark scheme on the MEI website confused me.

Thanks,
Sora
Since , what's in terms of ?
3. I'm not sure. Matrices is the only thing I don't understand in FP1.
4. I would just multiply A by all the options (a,b,c,d) until I got the identity matrix.
5. (Original post by Sora)
I'm not sure. Matrices is the only thing I don't understand in FP1.
Perhaps if we rewrite it:

Hence
6. A^-1 = A^2 ?
7. (Original post by Sora)
A^-1 = A^2 ?
Yep!
8. Not entirely sure how though. Can you explain please?
9. (Original post by Sora)
Not entirely sure how though. Can you explain please?
From

we can premultiply each side of the equation by

So.

Thus, in detail:

Obviously, you wouldn't need to put all that detail in, in an answer; I've just included it for your understanding.
10. Is that A(A^-1) = I = A^3?

then A^-1 = A^2
11. Sort of get it now, thanks.
12. Anyone done any work/learning on n x n matrices?

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