| 1)[4]√ab^3÷[12]√a^6b×[6]√a^2b^-4 =[4]√ab^3÷√ab×[3]√ab^-4 =a^(1/4-1/2+1/3)b^(3+1-4)=a^(1/12)=[12]√a
2)√√√a=a^(1/2)^3=a^(1/8)=[8]√a
3)[3]√5÷[12]√5×[8]√25 =[3]√5÷[12]√5×[4]√5=5^(1/3-1/12+1/4)=5^(1/2)=√5
4)[3]√81+[3]√3+[3]√-24=3[3]√3+[3]√3+[3]√-1×[3]√3×2 =4×3^(1/3)+(1+√3i)/2×3^(1/3)×2=5×3^(1/3)+3^(1/2+1/3)i =5[3]√3+([6]√3^5)i
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