Thực hiện phép tính: a) ( 3 – xy2 )2 – ( 2 + xy2 )2
b) 9x2 – ( 3x – 4 )2
c) ( a – b2 )( a + b2 )
d) ( a2 + 2a + 3 )( a2 + 2a – 3 )
e) ( x – y + 6 )( x + y – 6 )
f) ( y + 2z – 3 )( y – 2z – 3 )

Choose the right classification of 5x + 3x^4 - 7x^3 + 10 by number terms and he degree 1. third degree polynomial 2. fourth degree polynomial 3. sixth degree polynomial 4. first degree binomial