4.9) 2.4p^5n^5
4.10) 625x^16/y^12
4.11) 6n^3/p^6
4.12) (3√5)^2/9=(√9*5)^2/9=(√45)^2/9=45/9=5
4.13) 2.8a^3b^7
4.14) 52^4/12b^6
4.16) ((7с+5)(3с-1)+(4с+6)(1-3с))/((1-3с)(3с-1))=
(21с^2+15c-7c-5+4c+6-12c^2-9c)/(3c-9c^2-1+3c)=
(9c^2-5c+1)/(9c^2+6c-1)
4.18) 45a^4b^5*b/9a^8=5b^6/a^4
4.19) ((5m-9)(2-m)-(3-2m)(m-2))/((m-2)(2-m))=
(10m-5m^2-18+9m-3m+2m^2+6-4m)/(2m-m^2-4+2m)=
(12m-3m^2-12)/(4m-m^2-4)
4.20) 28a/c^3*4a^2c=7/c^4a