1)(x²-1)-(x²+3x-2x-6)=0
x²-1-x²-3x+2x+6=0
-x=-5/:-1
x=5
2)(2x²+4x-x-2)-(2x²+x-10x-5)=0
2x²+3x-2-2x²+9x+5=0
12x=-3/:12
x=-1/4
3) 3x²+6x+3x+6=9+(3x²+6x-4x-8)
9x+6=9+2x-8
7x=-5/:7
x=-5/7
4) (10x²+20x+15x+30)-2(5x²-5x-4x+4)=12
10x²+35x+30-10x²+10x+8x-8-12=0
53x=-10/:53
x=-10/53