Помогите решить задания

Решите задачу:

$1)(a ^{4} ) ^{3} :a ^{3} =a ^{4*3-3} =a ^{12-3} =a ^{9}$

$2) p(x;y)=p _{1} (x;y)+p _{2} (x;y);+ p_{3} (x;y)=27 x^{3} -27 x^{2} y+ \\ +9xy ^{2} -y ^{3} +20 x^{3} -15 x^{2} y+4xy ^{2} -3y ^{3} +10 x^{3} +12 x^{2} y- \\ -5xy ^{2} +y ^{3} =57 x^{3} -30 x^{2} y+8xy ^{2} -3y ^{3}$

$3)(-2 x^{2} +7x)(x-5)=-2 x^{3} +10 x^{2} +7 x^{2} -35x= \\ =-2 x^{3} +17 x^{2} -35x$