Układy równań: 1.{2x=y+5 {2x=2y+7 3.{x+y=3,5 _______ 2 {x+1=y-2

1.{2x=y+5 /*(-1) {2x=2y+7 -2x=-y-5 2x=2y+7 -2x+y=-5 2x-2y=7 ---------- -y=2 y=-2 2x-2*(-2)=7 2x+4=7 2x=7-4 2x=3 x=3:2 x=1 1/2 x=1 1/2 y=-2 3.{x+y=3,5 /*2 _______ 2 {x+1=y-2 x+y=3,5*2 x-y=-2-1 x+y=7 x-y=-3 ------------ 2x=4 x=4:2 x=2 2+y=7 y=7-2 y=5 x=2 y=5