(lg根号8+lg27-lg根号1000)÷lg1.8 化简求值
问题描述:
(lg根号8+lg27-lg根号1000)÷lg1.8 化简求值
答
(lg√8+lg27-lg√1000)/lg1/8
=(lg2 (3/2)+lg3 3-lg10 3/2)/lg(18/10)
=(3/2lg2+3lg3-3/2)/(lg18-lg10)
=(3/2lg2+3lg3-3/2)/(lg2*9-1)
=(3/2lg2+3lg3-3/2)/(lg2+lg9-1)
=(3/2lg2+3lg3-3/2)/(lg2+lg9-1)
=3/2(lg2+lg9-1)/(lg2+lg9-1)
=3/2
loga b^c=cloga b(a为底数,b为真数,c为真数的次方)
loga MN=log aM+loga N(真数相乘等于对数相加)
loga M/N=log aM-loga N(真数相除等于对数相减)
loga a=1
loga 1=0
答
=(3/2ln2+3ln3-3/2)/(lg18-1)
=3/2(ln2+2ln3-1)/(ln2+2ln3-1)
=3/2