①-2ab(3a²-2ab-4b²)②(4y-1)(y+5)③(2a+b+3)(2a+b-3)④(2a+1)²-(2a+1)(-1+2a)

①-2ab(3a²-2ab-4b²)②(4y-1)(y+5)③(2a+b+3)(2a+b-3)④(2a+1)²-(2a+1)(-1+2a)
①-2ab(3a²-2ab-4b²)
②(4y-1)(y+5)
③(2a+b+3)(2a+b-3)
④(2a+1)²-(2a+1)(-1+2a)

①-2ab(3a²-2ab-4b²)②(4y-1)(y+5)③(2a+b+3)(2a+b-3)④(2a+1)²-(2a+1)(-1+2a)
①-2ab(3a²-2ab-4b²)=-6a^3b+4a^2b^2+8ab^3)
②(4y-1)(y+5)=4y^2+19y-5
③(2a+b+3)(2a+b-3)=(2a+b)^2-9=4a^2+b^2+4ab-9
④(2a+1)²-(2a+1)(-1+2a)=4a^2+1+4a-4a^2+1=4a+2

式子列在这是想干什么，展开？还是因式分解？