Х×(х+7)= х×(3х+2)+4×(х-1)= х×(1+х+y+d)=
Х·(х+7)=x²+7x х·(3х+2)+4·(х-1)=3x²+2x+4x-4=3x²+6x-4 х·(1+х+y+d)=x+x²+xy+xd