b^(3n-1) c^2/a^(2n+1)×a^(2n-1)/b^(3n-2)
= a^[(2n-1)-(2n+1)]b^[(3n-1)-(3n-2)] c^2
= a^[2n-1-2n-1]b^[3n-1-3n+2] c^2
= a^[-2]b^[1] c^2
= a^(-2)b c^2