对数计算问题设lga+lgb=2lg(a-2b),求log以4为底数,a/b为真数的值

Question

对数计算问题
设lga+lgb=2lg(a-2b),求log以4为底数,a/b为真数的值

Answer 1

lga+lgb=lgab=2lg(a-2b)
ab=(a-2b)^2
(a-4b)(a-b)=0
a/b=4或a/b=1
log4(a/b)=1
log4(a/b)=0