Odpowiedź:
(2x+y)(x-2y)-x(x+y)=2x2-4xy+xy-2y2-x2-xy=x2-2y2-5xy
(3a-2b)(a-b)+2(a-b)(a-2b)= 3a2-3ab-2ba+2b2+2(a2-2ab-ab+2b2)=3a2-5ab+2b2+2a2-4ab-2ab+4b2=5a2+6b2-ab
(4k+1)(2k-1)-(k-1)(k-3)=8k2-4k+2k-1-(k2-3k-k+3)=8k2-2k-1-k2+3k+k-3=7k2+2k-4
Szczegółowe wyjaśnienie:
