(lg2)²+(lg5)²+lg2xlg5=?
问题描述：
(lg2)²+(lg5)²+lg2xlg5=?
(lg2)²+(lg5)²+lg2xlg5=?麻烦您把步骤也写上
答
(lg2)²+(lg5)²+2lg2xlg5 加了一个2
=(lg2)²+(1-lg2)²+2lg2x(1-lg2)
=lg²2+1-2lg2+lg²2+2lg2-2lg²2
=1
其中lg5=lg(10/2)=lg10-lg2=1-lg2对不起我弄错了 是 (lg2)²+(lg5)²+lg2xlg25=lg2xlg25=2lg2lg5(lg2)²+(lg5)²+lg2xlg25=(lg2)²+(lg5)²+2lg2xlg5 =(lg2)²+(1-lg2)²+2lg2x(1-lg2)=lg²2+1-2lg2+lg²2+2lg2-2lg²2=1