1. Giải các phương trình:
a) (x²+x+1)(x²+x+2)=12
b) (x²+x+6)(x²+x+3)=6
c) (x²+5x)²-2(x²+5x)-24=0
d) (x²-4x)²+2(x²-4x)-8=0
e) (2-x²)²+3(2-x²)+2=0
f) (x²-6x)²-2(x-3)²=81
g) (x²+2x)²-(x+1)²=55
h) x(x+1)(x-1)(x+2)=24
i) (x-4)(x-5)(x-6)(x-7)=1680
j) (x+1)(x+2)(x+5)(x-2)=-20
k) (x+1)(x+2)(x+3)(x+4)=3
l) (x-2)(x-4)(x+6)(x+8)=-36
m) (x-1)(x-3)(x+5)(x+7)=297
n) (x+1)(x+3)(x+5)(x+7)=9
o) (8x+7)²(4x+3)(x+1)=4,5