log函数的简单计算(lg2)^2+lg5*lg20-1=_________ 求过程!

log函数的简单计算(lg2)^2+lg5*lg20-1=_________ 求过程!
log函数的简单计算
(lg2)^2+lg5*lg20-1=_________  求过程!

log函数的简单计算(lg2)^2+lg5*lg20-1=_________ 求过程!
(lg2)^2+lg5*lg20-1
=(lg2)^2+lg5*(lg2+lg10)-1
=(lg2)^2+lg5*lg2+lg5-1
=lg2*(lg2+lg5)+lg5-1
=lg2*lg10+lg5-1
=lg2+lg5-1
=lg10-1
=0

原式=（lg2）^2+lg5*(2lg2+lg5)-1
= (lg2)^2+2lg5 * lg2 +(lg5)^2 -1
= (lg2 +lg5 )^2 -1
= 1-1
=0