某项工程,甲单独做所需天数是乙,丙两队合作所需天数的A倍;

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  • 设甲、乙、丙单独做各需xyz天

    x=a(y+z) a=x/y+z a+1=x+y+z/y+z 1/a+1=y+z/x+y+z

    y=b(x+z) b=y/x+z b+1=x+y+z/x+z 1/b+1=x+z/x+y+z

    z=c(x+y) c=z/x+y c+1=x+y+z/x+y 1/c+1=x+y/x+y+z

    1/(a+z)+1/(b+1)+1/(c+1)

    = (y+z)/(x+y+z)+(x+z)/(x+y+z)+(x+y)/(x+y+z)

    =2((x+y+z)/(x+y+z)

    =2

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