极品家丁 粤语:我想再问一个数学题,谢谢!!
来源:百度文库 编辑:中科新闻网 时间:2024/10/07 01:50:00
(lg2)^2*lg(250)+(lg5)^2*lg(40)=??
谢谢各位老师!!谢..
谢谢各位老师!!谢..
lg250=lg(10*5^2)=lg10+lg5^2=1+2lg5
lg40=lg(10*2^2)=1+2lg2
原式=lg2*lg2*(1+2lg5)+lg5*lg5*(1+2lg2)
=lg2*lg2+2lg2*lg2*lg5+lg5*lg5+2lg2*lg5*lg5
=lg2*lg2+2lg2*lg5(lg2+lg5)+lg5*lg5
=lg2*lg2+2lg2*lg5+lg5*lg5
=(lg2+lg5)^2
=1
难啊~~~~~我才13阿~~~我想这个是高中的把