а) скорее всего опечатка в знаменателе
(7^11 *9^11 ) / (63^5)^2 =
= (7*9)^11 / 63^ (5*2)=
= 63^11 / 63^10 = 63 ^ (11-10) =
= 63 ^1 = 63
б)
(13^6 *2^6 ) / (26^5) =
= (13*2)^6 / (26^5) =
= 26^6 /26^5 = 26^(6-5)=
= 26^1 =26
в)
(12^2 *35^3 ) / (28^2 *15^4) =
= (12^2 * 35^2 *35^1 ) / (28^2 * 15^2 * 15^2) =
= ( (12*35)^2 * 35 ) / ((28*15)^2 * 15^2)=
= 420^2 * 35 / 420^2 * 15^2 =
= (7*5) / (3*5)^2 =
= (7 *5 ) / (3^2 *5^2 )=
= 7/ (9*5)= 7/45