3^a×5^b=15
3^(a-1)×5^(b-1)=1
3^(a-1)=1/5^(b-1)=5^(1-b)
[3^(a-1)]^(1-d)=[5^(1-b)]^(1-d) 两边进行(1-d)次方
同理:3^(c-1)=5^(1-d)
[3^(c-1)]^(1-b)=[5^(1-d)]^(1-b)]
∴[3^(a-1)]^(1-d)=[3^(c-1)]^(1-b)
∴(a-1)(1-d)=(c-1)(1-b)
即(a-1)(d-1)=(c-1)(b-1)
3^a×5^b=15
3^(a-1)×5^(b-1)=1
3^(a-1)=1/5^(b-1)=5^(1-b)
[3^(a-1)]^(1-d)=[5^(1-b)]^(1-d) 两边进行(1-d)次方
同理:3^(c-1)=5^(1-d)
[3^(c-1)]^(1-b)=[5^(1-d)]^(1-b)]
∴[3^(a-1)]^(1-d)=[3^(c-1)]^(1-b)
∴(a-1)(1-d)=(c-1)(1-b)
即(a-1)(d-1)=(c-1)(b-1)