Dear Sylvain,

I am using ’\startalign’

\starttext
\startformula
\eqalign{
ax^2+bx+c &= 0 \cr
x &= \frac{-b \pm \sqrt{b^2-4ac}}{2a} \cr
}
\stopformula
\stoptext

\starttext

\startformula

\startalign

\NC ax^2 + bx + c \NC = 0 \NR

\NC x \NC = = \frac{-b \pm \sqrt{b^2-4ac}}{2a} \NR

\stopalign

\stopformula

\stoptext

There is a nice guide book "My Way” for math-alignment by Aditya.

Best regards,

Dalyoung