2x/7-2/3+x(x-2)=(x-3)²/9
2x/7-2/3+x²-2x=(x²-6x+9)/9
(2x-14+21x²-42x)/21=(x²-6x+9)/9
(21x²-40x-14)/21=(x²-6x+9)/9
9(21x²-40x-14)=21(x²-6x+9) :3
3(21x²-40x-14)=7(x²-6x+9)
63x²-120x-42=7x²-42x+63
63x²-7x²-120x+42x-42-63=0
56x²-78x-105=0
Δ=6084+23520=29604
nu stiu daca e scris bine ex.