X十2y一3Z=0,2X十3y十5Z=0求X十y十Z/X一y十Z的值
问题描述:
X十2y一3Z=0,2X十3y十5Z=0求X十y十Z/X一y十Z的值
答
x+2y-3z=0 (1) 2x+3y+5z=0 (2) (2)*2-(1)*3 4x+6y+10z-3x-6y+9z=0 x+19z=0 x=-19z (1)*2-(2) 2x+4y-6z-2x-3y-5z=0 y-11z=0 y=11z (x+y+z)÷(x-y+z) =(-19z+11z+z)/(-19z-11z+z) =-7z/(-29z) =7/29