Question

（lg2)^2+lg5·lg20-1=?

Answer 1

（lg2)^2+lg5·lg20-1

=(lg2)^2+lg5*lg(2*10)-1

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

=(lg2)^2+lg2*lg5+lg5-1

=lg2*(lg2+lg5)+lg5-1

=lg2*lg10+lg5-1

=lg2+lg5-1

=lg(2*5)-1

=1-1

=0