Question

2lg5+(lg2)^3*(2lg5+lg2)计算~

Answer 1

设x=lg5,lg2=1-lg5=1-x

2x+(1-x)^3(1+x)

=2x+(1-x)^2(1-x^2)

=2x+(x^2-2x+1)(1-x^2)

=2x+x^2-x^4-2x+2x^3+1-x^2

=-x^4+2x^3+1

=x^3(2-x)+1

=(lg5)^3*lg20+1

好像只能化到这了,不知道了.