Question

Визначити x-y, якщо |x-y| + |12-x|=0

Answer 1

$\begin{cases} x-y=0 \\ 12-x=0 \end{cases} \ \textless \ =\ \textgreater \ \begin{cases} x=y \\ x=12 \end{cases} \ \textless \ =\ \textgreater \ \begin{cases} x =12 \\ y=12 \end{cases} =\ \textgreater \ \\ \\ x-y=12-12=0$