3x + 5y = 12 3x + 5y = 12 3x+5y-3x+6y=12+21 11y= 33 y= 3
x - 2y = - 7| ×(-3) -3x+6y=21 -3x+6y=21 -3x+6y=21 -3x+6y=21
y= 3 y= 3 y= 3 y= 3
-3x+6×3=21 -3x=21-18 -3x=3 x=-1
или
3x + 5y = 12 3x + 5y = 12 3(-7+2y)+5y=12 -21+6y+5y=12 11y=33
x - 2y = - 7 x = - 7+2y x = - 7+2y x = - 7+2y x = - 7+2y
y=3 y=3
x = - 7+2×3 x=-1