已知3分之x等于5分之y等于4分之z,求y分之xyz和y
分式的加减
已知x/3=y/5=z/4,求(x+y+z)/y和(x+y-z)/(y-x) 解: 令x/3=y/5=z/4=t 则x=3t y=5t z=4t (x+y+z)/y=(3t+5t+4t)/5t=12/5 (x+y-z)/(y-x)=(3t+5t-4t)/(5t-3t)=2