lg5^2+lg4+lg5*lg20+(lg2)^2
=lg25+lg4+lg5*(1+lg2)+(lg2)^2
=lg25×4+lg5+lg5lg2+(lg2)^2
=lg100+lg5+lg2(lg5+lg2)
=2+lg5+lg2
=2+lg10
=3
lg5^2+lg4+lg5*lg20+(lg2)^2
=lg25+lg4+lg5*(1+lg2)+(lg2)^2
=lg25×4+lg5+lg5lg2+(lg2)^2
=lg100+lg5+lg2(lg5+lg2)
=2+lg5+lg2
=2+lg10
=3