已知lgb/lga+lga/lgb=5/2 求(a^3+b^3)/(ab+a^2b^2)
(a^3+b^3)/(ab+a^2b^2)
=（a+b）(a^2-ab+B^2) /(ab+a^2b^2)
lgb/lga+lga/lgb=5/2
====> lg(b-a) + lg (a-b)=lg10^(5/2)=
===> lg(b-a)(a-b)=lg10^(5/2)
====> (b-a)(a-b)=10^(5/2)
====> -(a-b)^2=10^(5/2)
已知lgb/lga+lga/lgb=5/2 求a3+b3/(ab+a2b2)
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