A1)
(a+b)(c-d)= ac-ad+bc-bd
OTBET: 1
A2)
(x²y-y²+xy)(x²-2)= x^4y-x²y²+x³y-2x²y+2y²-2xy
OTBET: 3
A3)
(3a-7b)(2a+3b)+5ab= 6a²+9ab-14ab-21b²+5ab=6a²-21b²
OTBET: 2
A4)
A(b-c)-(2b-2c)= a(b-c)-2(b-c)=(b-c)(a-2)
OTBET: 2
A5)
Ax+bx-ay-by=x(a+b)-y(a+b)=(a+b)(x-y)
OTBET:4