4.17^x=1000,4.17=1000^(1/x)
417^y=1000,417=1000^(1/y)
4.17/417=1000^(1/x)/1000^(1/y)
0.01=1000^(1/x-1/y)
10^-2=10^3(1/x-1/y)
所以：
-2=3(1/x-1/y)
1/x-1/y=-2/3
(-8/27)^(1/x-1/y)
=(-8/27)^(-2/3)
=(-2/3)[3*(-2/3)]
=(-2/3)^-2
=9/4