化简求值：（3/4a^4b^7+1/18a^3b^8-1/9a^2b^6）÷（-1/3ab^3）^2,其中a=1/2,b
化简求值：（3/4a^4b^7+1/18a^3b^8-1/9a^2b^6）÷（-1/3ab^3）^2,其中a=1/2,b=-4
赞 fuchun2001 幼苗
共回答了22个问题采纳率：95.5% 举报
（3/4a^4b^7+1/18a^3b^8-1/9a^2b^6）÷（-1/3ab^3）^2
=（3/4a^4b^7+1/18a^3b^8-1/9a^2b^6）÷(-1/9a^2b^6)
=3/4a^4b^7÷(-1/9a^2b^6)+1/18a^3b^8÷(-1/9a^2b^6)-1/9a^2b^6÷(-1/9a^2b^6)
=-27/4a^2b-1/2ab^2+1
=27/4-4+1
=15/4
=（3/4a^4b^7+1/18a^3b^8-1/9a^2b^6）÷(-1/9a^2b^6)
=3/4a^4b^7÷(-1/9a^2b^6)+1/18a^3b^8÷(-1/9a^2b^6)-1/9a^2b^6÷(-1/9a^2b^6)
=-27/4a^2b-1/2ab^2+1
=27/4-4+1
=15/4
1年前
9
shenlongying 幼苗
共回答了15个问题采纳率：80% 举报
（3/4a^3+1/2a^3b^3-1/9a^2b^4）/(-1/3ab)^2
=(a^2/36)（27a+18ab^3-4b^4）/(1/9a^2b^2)
=(27a+18ab^3-4b^4）/4b^2
=27a/4b^2+9ab/2-b^2
=27*(1/2)/4*(-4)^2+9*(1/2)*4/2-(-4)^2
=27/128-7
=-869/128
=(a^2/36)（27a+18ab^3-4b^4）/(1/9a^2b^2)
=(27a+18ab^3-4b^4）/4b^2
=27a/4b^2+9ab/2-b^2
=27*(1/2)/4*(-4)^2+9*(1/2)*4/2-(-4)^2
=27/128-7
=-869/128
1年前
0
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