(lg2)^2+lg2*lg5+(lg5)^2=
问题描述：
(lg2)^2+lg2*lg5+(lg5)^2=
答
(lg2)^2+lg2*lg5+(lg5)^2
=2(lg2) + lg(2+5)+2(lg5)
=2(lg2+lg5)+lg7
=2lg(2×5)+lg7
=2lg10+lg7
=2+lg7有lg2*lg5= lg(2+5）公式嗎？？？？！！！是(lg2)^2而不是lg(2^2)!!(lg2)^2+lg2*lg5+(lg5)^2==(lg2)(lg2)+2*lg2*lg5+(lg5)(lg5)-lg2*lg5=(lg2)(lg2+lg5)+(lg5)(lg5+lg2)-lg2*lg5=lg2*lg10+lg5*lg10-lg2*lg5=lg2+lg5-lg2*lg5lg2+lg5不是等於1嗎？？？