[4(3x+2)-3(2x+1)]* [[4(3x+20+3(2x+1)] = (12x+8-6x-3)(12x+8+6x+3)=
(6x+5) (18x+11)
2; ai ceva gresit in text, nu se descompune
daca notezi pe x²=y
ai y²-y+1 care nu se descompune (se demonstreza in clasa a 9-a)
dar putem forta ceva
x^4-x²+1= x^4+2x²+1-3x²=(x²+1)²-3x²= (x²+1)²-(x√3)²= (x²-x√3+1) (x²+x√3+1)
3.x²-x-6=x²-3x+2x-6= x(x-3)+2(x-3)
=(x-3)(x+2)
4....Observam ca:
16x²=(4x)²
25=5²
40x= 2*4x*5
atunci
16x²-40x+25=(4x-5)² dar la fel de bine se poate si (5-4x)²
