А)2x(3x-y)+y(x-2y) d)(a-4)²-2a(a-4) c)6-x(x+1)=9-x² n)6(x-2)=7x-(3x+1)

a) 6x2-2xy+xy-2y2=6x2-xy-2y2
d)a2-8a+16-2a2+8a=16-a2
c)6-x2-x--9+x2=0
   -x-3=0
   x=-3
n)6x-12-7x+3x+1=0
   2x=11
    x=5,5