1) (x+2y) ²
2) 25t²-(2z+3t)²
3) -c (-d-3)²
4) 3 (2a+5)²+5 (2a-3)²

1) x²+2x+2y+(2y)²x²+4xy+4y²2) (5t-(2z+3t))•(5t+(2z+3t))(5t-2z-3t)•(5t+2z+3t)(2t-2z)•(8t+2z)2(t-z)•2(4t+z)2•2(t-z)•(4t+z)4(t-z)•(4t+z)3) -c•(-(d+3))²-c•(d+3)²-c•(d²+6d+9)-cd²-6cd-9c4) 3(4a²+20a+25)+5(4a²-12a+9)12a²+60a+75+20 a²-60a+4532a²+120.