(3/7)^5*(8/21)^0*(9/7)^4

(3/7)^5*(8/21)^0*(9/7)^4
=(3^5/7^5)*(9^4/7^4)
=(3^5/7^5)*(3^8/7^4)
=3^13/7^9
{[b√(ab)]³*³√(a²b)}/³√(ab²)
=b^(1+3/2+1/3-2/3)*a^(3/2+1-1/3)
=b^(2+5/6)*a^(2+1/6)
=(ab)²*b^(5/6)*a^(1/6)
[a²*³√(a²b)]/√(ab)
=a^(2+2/2-1/2)*b^(1/2-1/2)
=a^(2+1/2)*b^0
=a^(5/2)
=a²√a

（3/7）^5*(8/21)^0*(9/7)^4
=3^5*7^(-5)*1*3^8*7(-4)
=3^13/7^9
=1594323/40353607.