1.(a - x)(x -y^{3}) <span> - (x - y)(a</span><span> - x</span>)=
(а-х)(х-у)(х2+ху+у2) - (х-у)(а-х)(а2+ах+х2)=
(а-х)(х-у)(х2+ху+у2-а2-ах-х2)=
(а-х)(х-у)(у2-а2+ху-ах)=(а-х)(х-у)((у-а)(у+а)+х(у-а))=(а-х)(х-у)(у-а)(у+а+х)
2. a<span> - 25 - 2a(a</span><span> - 25) + a</span>(a<span> - 25)=(а2-25)(1-2а+а2)=(а-5)(а+5)(1-а)^2</span>
3. n3<span> +an2</span><span> - n - a=n2(n+a)-(n+a)=(n+a)(n2-1)=(n+a)(n-1)(n+1)</span>
4. b<span> -bc - a</span> + ac = (b2-a2)-c(b-a) = (b-a)(b+a)-c(b-a)=(b-a)(b+a-c)
7a/6c -(49a²+36c²)/42ac+(6c-49a)/7a=
=(49a²-49a²-36c²+36c²-6c*49a)/42ac=-6c*49a/42ac=-7