28.
(8v + v² + 16)/(15v²+3v) : (16-v²)/(25v²-1) =
= (v + 4) / 3*(5v + 1) : (4 - v)(4 + v) / (5v - 1)(5v + 1) =
= (v + 4) / 3*(5v + 1) * (5v - 1)(5v + 1) / (4 - v)(4 + v) =
= (5v - 1) / 3*(4 - v).
29.
(k²+3k+2) / (k² + 7k+12) * (k-3)(k+3) / (k+1)(k-1) =
(k+1)(k+2) / (k+3)(k+4) * (k-3)(k+3) / (k+1)(k-1) =
= (k+2) / (k+4) * (k-3) / (k-1) =
= (k + 2)(k - 3) / (k + 4)(k - 1).
30.
(k²+5k+4) / (k²+5k+6) * (k-2)(k+2) / (k+4)(k-4) =
= (k+1)(k+4) / (k+3)(k+2) * (k-2)(k+2) / (k+4)(k-4) =
= (k+1) / (k+3) * (k-2) / (k-4) =
= (k + 1)(k - 2) / (k + 3)(k - 4)