lg的3次方 2+lg的3次方 5+3lg2*lg5 求值
问题描述：
lg的3次方 2+lg的3次方 5+3lg2*lg5 求值
答
lg^3(2)+lg^2(5)+3lg2*lg5=(lg2)^3+(lg5)^3+3lg2*lg5=(lg2+lg5)[lg^2(2)-lg2*lg5+lg^2(5)]+3lg2*lg5=lg10[(lg2)^2-lg2*lg5+(lg5)^2]+3lg2*lg5=(lg2)^2-lg2*lg5+(lg5)^2+3lg2*lg5=(lg2)^2+2lg2*lg5+(lg5)^2=(lg2+lg5)...