What does the symbol k means in the nest statement?

[YehiaMedhat]

Multiplication of any two matrices in [imath]M_n \mathbb{(K)}[/imath] is always possible, and the resulting product is again a square matrix of order n. Moreover, in [imath]M_n \mathbb{(K)}[/imath], by Proposition 1.14, [imath]I_n[/imath] is the multiplication identity, that is, for all [imath]A \in {M_n \mathbb{K}}[/imath],[math]AI=A=I[/math]This is from a linear algebra book, but I don't know what the symbol [imath]M_n \mathbb{(K)}[/imath] means.

 

[Dr.Peterson]

Multiplication of any two matrices in [imath]M_n \mathbb{(K)}[/imath] is always possible, and the resulting product is again a square matrix of order n. Moreover, in [imath]M_n \mathbb{(K)}[/imath], by Proposition 1.14, [imath]I_n[/imath] is the multiplication identity, that is, for all [imath]A \in {M_n \mathbb{K}}[/imath],[math]AI=A=I[/math]This is from a linear algebra book, but I don't know what the symbol [imath]M_n \mathbb{(K)}[/imath] means.

The book will surely have defined the notation. Look at the start of the chapter, or see if there is an index of notation.

I would expect this to mean "the set of n x n matrices over a field K". In fact, I searched for a phrase from your quote and found what is presumably your book; in section 1.1 it says (having identified K as a field)

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It's a good idea to read a chapter through twice, in order to pick up the second time any details you missed at first!

 

[YehiaMedhat]

Ok I'll do. Thanks ?