Question

Решите систему
2х-у=-4
5х+2у=-1

Answer 1

$2x-y=-4/*2\\5x+2y=-1\\\\4x-2y=-8\\5x+2y=-1\\9x=-9\\x=-1\\ \\ -5+2y=-1\\2y=-1+5\\2y=4\\y=2 \\ \\ \left \{ {{y=2} \atop {x=-1}} \right.$

Answer 2

2x-y=-4⇒y=2x+4
5x+2y=-1
5x+4x+8=-1
9x=-1-8
9x=-9
x=-9:9
x=-1
y=2*(-1)+4
y=-2+4
y=2
(-1;2)