对数lg2*lg5=?2lg(5)+2/3 lg8+lg5*lg20+lg2 =lg5^2+lg8^(2/3)+lg5*(lg4+lg5)+lg2 =lg100+lg5+2lg2*lg5+lg2 =2+(lg5+lg2) =2+1 =3 第二个等号lg5*(lg4+lg5)为什么=lg5+2lg2*lg5

来源:学生作业帮助网 编辑:作业帮 时间:2024/04/29 20:16:22
对数lg2*lg5=?2lg(5)+2/3 lg8+lg5*lg20+lg2 =lg5^2+lg8^(2/3)+lg5*(lg4+lg5)+lg2 =lg100+lg5+2lg2*lg5+lg2 =2+(lg5+lg2) =2+1 =3 第二个等号lg5*(lg4+lg5)为什么=lg5+2lg2*lg5

对数lg2*lg5=?2lg(5)+2/3 lg8+lg5*lg20+lg2 =lg5^2+lg8^(2/3)+lg5*(lg4+lg5)+lg2 =lg100+lg5+2lg2*lg5+lg2 =2+(lg5+lg2) =2+1 =3 第二个等号lg5*(lg4+lg5)为什么=lg5+2lg2*lg5
对数lg2*lg5=?
2lg(5)+2/3 lg8+lg5*lg20+lg2 =lg5^2+lg8^(2/3)+lg5*(lg4+lg5)+lg2 =lg100+lg5+2lg2*lg5+lg2 =2+(lg5+lg2) =2+1 =3 第二个等号lg5*(lg4+lg5)为什么=lg5+2lg2*lg5

对数lg2*lg5=?2lg(5)+2/3 lg8+lg5*lg20+lg2 =lg5^2+lg8^(2/3)+lg5*(lg4+lg5)+lg2 =lg100+lg5+2lg2*lg5+lg2 =2+(lg5+lg2) =2+1 =3 第二个等号lg5*(lg4+lg5)为什么=lg5+2lg2*lg5
2lg5+2/3 lg8+lg5*lg20+lg2
=lg5^2+lg8^(2/3)+lg5*(lg4+lg5)+lg2
=lg25+lg4+lg5*(lg4+lg5)+lg2
=lg100+lg5*(lg4+lg5)+lg2
=lg100+lg5*lg4+lg5*lg5+lg2
=lg100+(lg5)²+2lg2*lg5+lg2
lg5*(lg4+lg5)
=lg5*(lg2²+lg5)
=lg5*(2lg2+lg5)
=(lg5)²+2lg2*lg5
楼主的问题只能得到这个结果
楼主给出的计算是不正确的,若要得到最后的结果,必须将lg2换为(lg2)²
这样才有
原式=lg100+(lg5)²+2lg2*lg5+(lg2)²
=2+(lg5+lg2)²
=2+1²
=3