-(2a^2-b)^2=-(4a^4-4a^2b+b^2)=14a^4+4a^2b-b^2
-(3x+2y)^2=-(9x^2+12xy+4y^2)=-9x^2-12xy-4y^2
-(c^2+2d)^2=-(c^4+4c^2d+4d^2)=-c^4-4c^2d-4d^2
-(2a^2-b)^2=-(4a^4-4a^2b+b^2)=14a^4+4a^2b-b^2
-(3x+2y)^2=-(9x^2+12xy+4y^2)=-9x^2-12xy-4y^2
-(c^2+2d)^2=-(c^4+4c^2d+4d^2)=-c^4-4c^2d-4d^2