Question

HEI......ma puteti ajuta cu un exercitiu la mate.....
a) (a-b)(a+3b)+(2a-b)(a+2b)-(a+b)(a+b)(a-2b)
b) (2-x)(x+x la 2)-x la 2 (3+x)+8+(x+2)(5+x la 2)
SI ATAT ! MULTUMESC! DAU RASPUNS CASTIGATOR PRIMULUI CARE RASPUNDE !

Answer 1

$a).(a-b)(a+3b)+(2a-b)(a+2b)-(a+b)(a+b)(a-2b)= \\ =a^2+3ab-ab-3b^2+2a^2+4ab-ab-2b^2-(a+b)^2(a-2b)= \\ =3a^2+5ab-5b^2-(a^2+2ab+b^2)(a-2b)= \\ =3a^2+5ab-5b^2-(a^3-2a^2b+2a^2b-4ab^2+ab^2-2b^3)= \\ =3a^2+5ab-5b^2-a^3+3ab^2+2b^3$
$b).(2-x)(x+x^2)-x^2(3+x)+8+(x+2)(5+x^2)= \\ =2x+2x^2-x^2-x^3-3x^2-x^3+8+5x+x^3+10+2x^2= \\ =-x^3+7x+18$