1)(5a-7)(3a+1)=15a^2+5a-21a-7=15a^2-16a-7
2) (5y^2-1)(3y^2-1)=15y^4-5y^2-3y^2+1=15y^4-8y^2+1
3)(7y-1)(y^2-5y+1)=7y^3-35y^2+7y-y^2+5y-1=
7y^3-36y^2+12y-1
4) 3b(b-2)(2+4b)=(3b^2-6b)(2+4b)=
6b^2+12b^3-12b-24b^2=12b^3-18b^2-12b
Кажись все
5) ((a^1/3-b^1/3)*(ab)^1/3(a^2/3-b^2/3))/(ab)^1/3*(a^1/3+b^1/3)=(a^1/3-b^1/3)^2
3) =sqrt(a)(sqrt(a)-9)/7(a^1/4+3))=sqrt(a)(a^1/4-3)/7
=1/(sqrt(x)-1)
4)
(3/4)^3/5=(9/12)^3/5<(11/12)^3/5
1) esli a8=8 a15=-27 togda... ispolzuvaem formula An=An+(n-k)d. i poluchim otvet 43