Question

[(lg5)^2--(lg2)^2]/(lg25--lg4)等于(请写过程)

Answer 1

[(lg5)^2--(lg2)^2]/(lg25--lg4)

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

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

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

=(lg5+lg2)/2