Question

x-y+2=0
x+4=0
Вычтем из первого x-y+2=0
уравнения второе -
x+4=0
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??x+??y+??=0

Answer 1

$x-y+2=0\x+4=0\--------\\x-y+2-(x+4)=0-0\underline {x}-y+underline {underline {2}}-underline {x}-underline {underline {4}}=0\\-y-2=0; ; ; Rightarrow ; ; ; y+2=0; ,; y=2$