2.3*x+2.7*y+2.9*z=30 求X Y Z (是整数) 急

求所有三元组(x,y,z),满足x,y,z是正有理数,且x+1/y,y+1/z,z+1/x都是整数. 110*x+90*y+100*z=1000 x,y,z是整数 这种类型的题目怎么求? x y z x+y--- = --- = ---- ----y+Z z+x x+y ,求 z 的值 .求 x+y---- 已知x+y-z/z=x-y+z/y=-x+y+z/x,且xyz不等于0,求分式[(x+y)(x+z)(y+z)]/xyz 若z分之x+y+z=y分之x-y+z=x分之-x+y+z,求xyz分之(x+y)(y+z)(z+x) y+z÷x=Z+X÷y=X+Y÷z,X+Y+Z不等0求X+Y-Z÷X+Y+z值 (x+y-z)/z=(y+z-x)/x=(z+x-y)/y 求(x+y)(y+z)(z+x)/xyz x分之y+z=y分之z+x=z分之x+y(x+y+z不等于0）,求x+y+z分之x+y-z 已知：(x+y-z)/z=(x-y+z)/y+(y+z-x)/x,且xyz≠0,求代数式[(x+y)(y+z)(x+z) 设X,Y,Z都是整数,满足条件(X-Y)(Y-Z)(Z-X)=X+Y+Z,试证明X+Y+Z能被27整除 (x+y-z)(x-y+z)= 1.已知x:y:z=4:5:7,求：（一）2x+3y+z/5z； （二）x+y/y+z 非常急,