log3(x-1)=log9(x-5) 求x
问题描述：
log3(x-1)=log9(x-5) 求x
答
x-1=(x-5)^0.5…得x=自己算
答
对数有意义,x-1>0 x-5>0,解得x>5
log3(x-1)=log9(x-5)
log9(x-1)²=log9(x-5)
(x-1)²=x-5
整理,得
x²-3x+6=0
x²-3x+6=(x-3/2)²+15/4恒>0,方程无解.
log3(x-1)=log9(x-5) 方程无解.