等比数列中a1*a8=a2*a7=a3*a6=a4*a5
lga1+lga2+…+lga8=lg(a1*a2*a3*…*a8)
=lg[(a1*a8)*(a2*a7)*…*(a4*a5)]
=lg(a4*a5)^4
=4lg(a4*a5)
=4×lg(2×5)
=4
等比数列中a1*a8=a2*a7=a3*a6=a4*a5
lga1+lga2+…+lga8=lg(a1*a2*a3*…*a8)
=lg[(a1*a8)*(a2*a7)*…*(a4*a5)]
=lg(a4*a5)^4
=4lg(a4*a5)
=4×lg(2×5)
=4