rozwiąż układy równań metodą podstawiania. 1.{x+y=7 x-y=1 2.{2x -y=4 x+y=11 3.{x-2y= -3 2x+3y=8 prosze o pomoc.dam naj;)

1.{x+y=7 x-y=1 ------ 2x = 8 x =4 x+y = 7 4+y=7 y=3 x=4 2.{2x -y=4 x+y=11 ------- 3x= 15 x=5 x+y= 11 5+y = 11 y= 6 x=5 3.{x-2y= -3 | *(-2) 2x+3y=8 { -2x + 4y = 6 2x+3y=8 --------- 7y = 14 y= 2 2x + 3*2 = 8 2x = 2 x = 1 y = 2

1. {x+y=7 x-y=1 x=7-y 7-y-y=1 -2y=-6 y=3 x=7-3 x=4 2. {2x -y=4 x+y=11 x=11-y 2(11-y)-y=4 22-2y-y=4 -3y=-18 y=6 x=11-6 x=5 3. {x-2y= -3 2x+3y=8 x=-3+2y 2(-3+2y)+3y=8 -6+4y+3y=8 7y=14 y=2 x=-3+2*2 x=-3+4 x=1