(1.75^(1)*4^(2)*28^(8))^(1/9)=(1.75*4^(2)*4^(8)*7^(8))^1/9=(1.75*4^(10)*7^(8))^1/9

1.75^(1/9)*4*4^(1/9)*7^(8/9)=(1.75*4)^(1/9)*7^(8/9)*4

7^(1/9)*7^(8/9)*4=7*4=28