若a-2b=0,则log3(a^2 - b^2)- 2log3(a+ b)的值为若a-2b=0,则 log3(a^2 - b^2)_数学解答

若a-2b=0,则log3(a^2 - b^2)- 2log3(a+ b)的值为
若a-2b=0,
则 log3(a^2 - b^2) - 2log3(a+b) 的值为

人气：341 ℃　时间：2020-04-16 16:37:20

解答

a-2b=0
a=2b
所以
log3(a^2 - b^2) - 2log3(a+b)
=log3(a+b)(a-b)/(a+b)^2
=log3(a-b)/(a+b)
=log3(2b-b)/(2b+b)
=log3(1/3)
=-1