(-3/7-5/14-8/21)*3/14+5/6=(-18/42-15/42-16/42)*3/14+5/6=-49/42*3/14+5/6=
=-(49*3)/(42*14)+5/6=-1/4+5/6=-3/12+10/12=7/12
А) (3а-2b)²=(3a)²-2•3a•2b+(2b)²=9a²-12ab+4b²
б) (3х-5у)(3х+5у)=(3х)²-(5у)²=9х²-25у²
в) 3а⁴(2а+b)²=3a⁴((2a)²+2•2a•b+b²)=
=3a⁴(4a²+4ab+b²)=
=3a⁴•4a²+3a⁴•4ab+3a⁴•b²=
=12a^6+12a^5b+3a⁴b²
Решение в низу...........