Please help me with indices. Thanks in advance?

If I have an expression x^(-n + 1),
is it correct/safe to do this:

x^(-n + 1) = x^[ -(n - 1) ]
1 / [x^(n - 1) ]

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If I had (2x + 3)^(-n + 1)
then
(2x + 3)^(-n + 1) = (2x + 3) / [ (2x + 3)^n ]
...........................= (2x + 3) / [ (2x + 3)(2x + 3)^(n - 1) ]
...........................= 1/[ (2x + 3)^(n - 1) ]

But if I just followed

x^(-n + 1) = x^[ -(n - 1) ]
1 / [x^(n - 1) ]

(2x + 3)^(-n + 1) = (2x + 3)^[ -(n - 1) ]
...........................=1/[ (2x + 3)^(n - 1) ]

I'm really not sure if what I'm doing here is correct.