lg5^2+23lg8+lg5lg20+(lg2)^2
=2lg5+2/3×3lg2+lg5×(lg5+lg4)+(lg2)^2
=2×(lg2+lg5)+(lg5)^2+2lg5lg2+(lg2)^2
=2lg10+(lg5+lg2)^2
=2+(lg10)^2
=2+1
=3
lg5^2+23lg8+lg5lg20+(lg2)^2
=2lg5+2/3×3lg2+lg5×(lg5+lg4)+(lg2)^2
=2×(lg2+lg5)+(lg5)^2+2lg5lg2+(lg2)^2
=2lg10+(lg5+lg2)^2
=2+(lg10)^2
=2+1
=3