Question

计算:(lg2)的平方+lg5乘以lg20减去1

Answer 1

lg2)^2+lg5*lg20-1

=(lg2)^2+lg5lg(4*5)-1

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

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

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

=(lg5+lg2)^2-1

=(lg10)^2-1

=1-1

=0