398. 1)(4x)^3
2)(3a^2)^3
3)(2m^3)^3
4)(-4xy^2)^3
5)(-2a^3b^2)^3
6)(0,3p*q^3)^3
388.
1) (4a^2+4ab+b^2)-(a^2-4ab+4b^2)=4a^2+4ab+b^2-a^2+4ab-4b^2=3a^2-3b^2+8ab
2) (x^2+2xy+y^2)-(y^2-4y+4)=x^2+2xy+y^2-y^2+4y-4=x^2+2xy+4y-4
3)(p^2+2pq+q^2)-(p^2-2pq+q^2)=p^2+2pq+q^2-p^2+2pq-q^2=2pq
4) (16a^2-8ab-b^2)-(4a^2+12ab+9b^2)=16a^2-8ab-b^2-4a^2-12ab-9b^2=12a^2-10b^2-20ab