How to mix left and center alignment in math blocks

Questions
,
1

Hi everyone,

I’m trying to find a clean way to mix left-aligned equations with centered elements inside a single math environment.

In a math block using alignment points (&), a line without any alignment points is rendered as if it has an alignment point at the end. In my example, this causes the dots.c to jump to the left of the equations rather than staying centered relative to the block:

$
  & L_1 = 0 \
  & L_2 - a_(2 1) a_(1 1)^(-1) L_1 = 0 \
  dots.c \
  & L_m - a_(m 1) a_(1 1)^(-1) L_1 = 0
$

I can get the desired visual result by using a grid, but it feels like a manual layout workaround.

$
  #grid(
    columns: 1,
    gutter: 1em,
    align: left,
    $L_1 = 0$,
    $L_2 - a_(2 1) a_(1 1)^(-1) L_1 = 0$,
    align(center, $dots.c$),
    $L_m - a_(m 1) a_(1 1)^(-1) L_1 = 0$,
  )
$

Question:

Is there a cleaner way to achieve this within a single $ ... $ block?

I am looking for a solution that avoids the overhead of a grid or manual layout adjustments. Ideally, is there a way to lines without & center themselves relative to the rest of the block?

I am aware of the similar question titled “How to add center-aligned columns in math mode?”. However, I couldn’t find a satisfying answer there, so I am posting this.