To simplify the first rational expression, we first factor the denominator of the first expression and try to simplify it:

x^2 - 8x + 16 = (x - 4)^2

Now, the expression becomes:

(x - 1) / (x - 4)^2

To simplify the second rational expression, we first factor the denominator of the second expression and try to simplify it:

16 - x^2 = (4 + x)(4 - x)

Now, the expression becomes:

(x + 2) / (4 + x)(4 - x)

So, the simplified rational expressions are:

(x - 1) / (x - 4)^2 and (x + 2) / (4 + x)(4 - x)