Question

calculati sistemul de ecuatii 2x-y=1
x+y=-4

Answer 1

2x-y=1    2x+4-x=1   x=-3
x+y=-4    y=-4-x       y=1

Answer 2

2x-y=1
x+y= - 4 ⇒ x= -4-y

2(-4-y) - y = 1
-8-2y-y =1
y=-3

x-3=-4
x=-1