Решите систему:

{ y=x+z;

{ 7x+20y=150;

{ 35z-7x=-220;

Молодец)

{ y=x+z; { 7x+20y=150;{ 35z-7x=-2207x+20y+35z+(-7x)=150+(-220)20y+35z=-7020y=-70-35z20y=-35(2+z)|÷20y=-1,75(2+z)у=x+zx=y-zx=-1,75(2+z)-zx=-3,5-1,75z-zx=-3,5-2,75z35z-7x=-22035z-7(-3,5-2,75z)=-22035z+24,5+19,25z=-22054,25z=-220-24,554,25z=-244,5|÷54,25z=-4,5069z=~-4,51y=-1,75(2+z)y=-1,75(2+(-4,51))y=(-1,75)×(-2,51)y=4,3925y~4,39x=-3,5-2,76zx=-3,5-2,75×(-4,51)x=-3,5+12,40258x=8,9025x~8,9Проверка:x+z=y8,9+(-4,51)=4,394,39=4,39-истина.7х+20у=1507×8,9+20×4,39=15062,3+87,85=150150,15~150-истина 35z-7x=-235×(-4,51)-7×8,9=-220-150,85-62,3=-220-220,15~-220-истина. Ответ: x~8,9; y~4,39; z~-4,51