原式=(lg2³+lg5³-lg2-lg5)/[lg10的1/2次方*lg(1/10)]-(log4 4/log4 5) *log4 5-0
=(3lg2-lg2+3lg5-lg5)/[(1/2)lg10*(lg1-lg10)]-1
=2(lg2+lg5)/[(1/2)*1*(0-1)]-1
=2lg(2*5)/(-1/2)-1
=-4lg10-1
=-4*1-1
=-4-1
=-5.
loga 1=0
loga a=1
loga (b*c)=loga b+loga c
loga (b/c)=loga b-loga c
loga b的m次方=mloga b;
换底公式 :loga b=logc b/(logc a);