Упростите выражение N308

1.(5а^4+3а^2b-b^3)-(3a^4-4a^2b-b^2)=5a^4+3a^2b-b^3-3a^4+4a^2b+b^2=2a^4+7a^2b-b^3+b^2 2.(12xy-10x^2+9y^2)-(-14x^2+9xy-14y^2)=12xy-10x^2+9y^2+14x^2-9xy+14y^2=4x^2+23y^2+3xy 3.(7ab^2-8ab+4a^2b)+(10ab-7a^2b)=7ab^2-8ab+4a^2b+10ab-7a^2b=4a^2b+2ab 4.(2c^2+3c)+(-c^2+c)-(c^2+4c-1)=2c^2+3c-c^2+c-c^2-4c+1=1