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2lg2+lg25%lg10怎么算

2lg2+lg25-lg10=lg4+lg25-lg10=lg 4×25 10 =lg10=1故答案为1

应该是(lg2)^2+lg2*lg5+lg5 吧. (lg2)^2+lg2*lg5+lg5 =(lg2)^2+lg2*lg(10/2)+lg(10/2) =(lg2)^2+lg2*(lg10-lg2)+lg10-lg2 =(lg2)^2+lg2*(1-lg2)+ 1-lg2 =(lg2)^2 +lg2 -(lg2)^2+ 1-lg2 =1.

(lg5)^2+2lg2-(lg2)^2 = (lg5)^2-(lg2)^2+2lg2 =(lg5+lg2)(lg5-lg2)+2lg2 =lg10·(lg5-lg2)+2lg2 =lg5-lg2+2lg2 =lg5+lg2 =lg10 =1

原式= 2/3*5/3*(lg3/lg2 * lg2/lg3) = 10/9 *(lg3*lg2 /(lg3*lg2) ) =10/9

由公式:lga+lgb=lgab; 则,lg5+lg2=lg(5×2)=lg10=1 (由对数函数定义及其与指数函数互为反函数的关系:10^1=10→lg10=1)

=lg2*lg(25*100)=lg2*(lg25+lg100)=lg2*(lg(5*5)+2)=lg2*(2lg(10/2)+2)=lg2*[2(lg10-lg2)+2]=lg2*[2(1-lg2)+2]=lg2*(4-2lg2)=4lg2-2(lg2)^2

lg2*lg2500+2(lg5)^2 =lg2(lg25+lg100)+2(lg5)^2 =lg2(2lg5+2)+2(lg5)^2 =2lg2lg5+2lg2+2(lg5)^2 =2lg5(lg2+lg5)+2lg2 =2lg5lg10+2lg2 =2lg5+2lg2 =2(lg2+lg5) =2lg10 =2

设 x = lg2 ,则 10^x = 2 , 因此 10^lg2 = 10^x = 2 。

答案是-1 原式=lg2x(lg5/2)+lg(1/5)x(log5x8) =lg2x(lg5-lg2)-lg5x(lg5+3lg2) =-((lg2)^2+(lg5)^2+2lg2lg5) =-(lg2+lg5)^2 =-(lg10)^2 =-1 不懂得地方问我

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