(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
(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