1) a) (c+2)(c-3)=c2-3c+2c-6=c2-c-6
б) (2а2-1)(3а+4)=6а2+8а-3а+4=6а2+5а+4
в) (5x-2y)(4x-y)=20x2-5xy-8xy+2y2=20x2-13xy+2y2
г) (a-2)(a2-3a+6)=a3-3a2+6a-2a2+6a-12=a3-5a2+12a-12
2) a) a(a+3)-2(a+3)=(a+3)(a-2)
б) ax-ay+5x-5y=(ax-ay)(5x-5y)=a(x-y)+5(x-y)=(x-y)(a+5)
4) a) x2-xy-4x+4y=x(x-y)-4(x-y)=(x-4)(x-y)
б) ab-ac-bx+cx+c-b=a(b-c)-x(b-c)-(b-c)=(b-c)(a-x-1)