化简
lg²5+（2+lg5）lg2+1/2lg25
=lg²5+2lg2+lg5lg2+lg5
=lg²5+lg2+(lg2+lg5)+lg5lg2+lg5
=lg²5+lg2+1+lg5lg2
=lg5(lg5+lg2)+lg2+1
=lg5+lg2+1
=1+1
=2