# Why Doesn't This Work

#### zylo

Consider Ax=0

$$\displaystyle \begin{vmatrix} a_1_1\\ a_2_1\\ a_3_1\\ a_4_1\\ a_5_1 \end{vmatrix}x_1 + \begin{vmatrix} a_1_2\\ a_2_2\\ a_3_2\\ a_4_2\\ a_5_2 \end{vmatrix} x_2 +\begin{vmatrix} a_1_3\\ a_2_3\\ a_3_3\\ a_4_3\\ a_5_3 \end{vmatrix} x_3 =0$$

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#### zylo

But this works!?

$$\displaystyle \begin{pmatrix} a1 &a2 &a3 \\ b1 &b2 &b3 \end{pmatrix} x_1=0$$

#### zylo

$$\displaystyle \begin{vmatrix} a11\\ a21\\ a31\\ a41\\ a51 \end{vmatrix}x1+\begin{vmatrix} a12\\ a22\\ a32\\ a42\\ a52 \end{vmatrix}x2+\begin{vmatrix} a13\\ a23\\ a33\\ a43\\ a53 \end{vmatrix}x3=0$$

It didn't like double subscripts in the matrix. a1_1 ok, a_1_1 ng

#### skipjack

Forum Staff
I suspect you want this:

$$\displaystyle \begin{vmatrix} a_{11} \\ a_{21} \\ a_{31} \\ a_{41} \\ a_{51} \end{vmatrix}x_1 + \begin{vmatrix} a_{12} \\ a_{22} \\ a_{32} \\ a_{42} \\ a_{52} \end{vmatrix} x_2 +\begin{vmatrix} a_{13} \\ a_{23} \\ a_{33} \\ a_{43} \\ a_{53} \end{vmatrix} x_3 = 0$$

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