解方程组X-Y+Z=A,X+Y-Z=B,-X+Y+Z=C(A,B,C为常数)
问题描述:
解方程组X-Y+Z=A,X+Y-Z=B,-X+Y+Z=C(A,B,C为常数)
答
A+B=2X X=(A+B)/2
B+C=2Y Y=(B+C)/2
A+C=2Z Z=(A+C)/2
答
X-Y+Z=A 1
X+Y-Z=B 2
-X+Y+Z=C 3
1+2+3:x+y+z=A+B+C 4
(4-1)/2:y=(B+C)/2
(4-2)/2:z=(A+C)/2
(4-3)/2:x=(A+B)/2