log3(x-1)=log9(x+5) 求x
问题描述:
log3(x-1)=log9(x+5) 求x
答
log(9)(x-1)²=log(9)(x+5)
∴(x-1)²=x+5
(x-4)(x+1)=0
∴x=4or-1
∵x-1>0
∴x=4