=(lg5)^2+lg2lg5+lg2

=lg5(lg5+lg2)+lg2

=lg5lg 10+lg2

=lg5+lg2

=lg 10

= 1

2) original formula = (lg5) 2+2lg2+(lg2+lg5)-(lg2) 2

=[(lg5)^2-(lg2)^2]+2lg2+(lg2+lg5)

=(lg5+lg2)(lg5-lg2)+2lg 2+(lg2+lg5)

=(lg5-lg2)+2lg2+(lg2+lg5)

=2(lg2+lg5)

=2lg 10

=2