Question

lgx*lgy=lg(x*y)吗?

Answer 1

lg(x*y)=lgx+lgy

log(a^2)b=1/2log(a)b

所以原式=[log(2)5+1/2*log(2)0.2][log(5)2+1/2log(5)0.5]

=1/2log(2)(10*0.2)*1/2log(5)(4*0.5)

=1/4*log(2)2log(5)2

=1/4*log(5)2