(Log2)的三次方+(Log5)的三次方+lg8*lg5
问题描述：
(Log2)的三次方+(Log5)的三次方+lg8*lg5
答
lg5=lg(10/2)=lg10-lg2=1-a log2 3是以2为底的3的对数并且log2 3＝lg3/lg2=b/a
答
(lg2)^3+(lg5)^3+lg8*lg5
=(lg2+lg5)((lg2)^2-lg2*lg5+(lg5)^2)+3lg2*lg5
=(lg2)^2+2lg2*lg5+(lg5)^2
=(lg2+lg5)^2=1