# Extract matrix from a system of linear equations [duplicate]

I have a big system of linear equations $f_i(x_1,...x_n)$ with $n$ variables and $n$ equations. I want to extract the matrix $M$ where $\vec{f}(\vec{x})=M\vec{x}$. For example if I have

$$f_1(x) = x + 2y \\ f_2(x) = 3x-y$$ then I want to get the matrix

{{1,2}, {3,-1}}.


Is there a way to do this in Mathematica?

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## marked as duplicate by Mr.Wizard♦Aug 1 '14 at 17:04

l = {x + 2 y, 3 x - y};