Why are the following determinant the same?

Question

I search on the internet but get no answers, could anybody help me please?

I mean which rule does it use?

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Add the last two columns to the first one. – May 11 '14 at 00:09 — , May 11 '14 at 00:09

score 1 · Accepted Answer · answered May 11 '14 at 00:28

1

You can swap one column (or line) by any linear combination of columns (or lines) without changing the determinant. Do the operation: $$L_1 := L_1 + L_2 + L_3$$

answered May 11 '14 at 00:28

Ivo Terek

77,665

Multiplying out two $3\times 3$ determinants and comparing the two resulting cubics wouldn't be that much harder... – DJohnM May 11 '14 at 01:52
@User58220 Yes, it wouldn't. But why bother, if we know the theory? (: – Ivo Terek May 11 '14 at 01:56

Why are the following determinant the same?

1 Answers1