To z równań z dwiema niewiadomymi z 2 gim. Trzeba Wyznaczyć x i y   1.{-(x+1)-2(y+1)=-5    {3x+5y=7 2.{2(8y-x)-(x-y)=-15    {3(x+y)-4(x-y)=-3   DAJE NAJ :)

1. -(x+1)-2(y+1)=-5 3x+5y=7   -x-1-2y-1=-5 3x+5y=-5   -x-2-2y=-5 3x+5y=7   -x-2y=-3 3x+5y=7   x+2y=3 3x+5y=7   x=3-2y 3(3-2y)+5y=7   x=3-2y 9-6y+5y=7   x=3-2y 9-y=7   x=3-2y -y=-2   x=3-2y y=2   x=3-2*2 y=2   x=3-4 y=2   x=-1 y=2   2. 2(8y-x)-(x-y)=-15 3(x+y)-4(x-y)=-3   16y-2x-x+y=-15 3x+3y-4x-4x=-3   17y-3x=-15 -x-y=-15   17y-3x=-15 x+y=15   17y-3x=-15 x=15-y   17y-3(15-y)=-15 x=15-y   17y-45+3y=-15 x=15-y   20y-45=-15 x=15-y   20y=30 x=15-y   y=3/2 x=15-3/2   y=3/2 = 1 i 1/2 x=13 i 1/2