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已知X+Y+Z=7,XY+YZ+ZX=14,XYZ=8(X+Y)(Y+Z)(Z+X)的值

题目详情
已知X+Y+Z=7,XY+YZ+ZX=14,XYZ=8 (X+Y)(Y+Z)(Z+X)的值
▼优质解答
答案和解析
x+y=7-z,y+z=7-x,x+z=7-y
(X+Y)(Y+Z)(Z+X)=(7-x)(7-y)(7-z)
=343-49(x+y+z)+7(xy+xz+yz)-xyz
=343-49*7+7*14+8
=106