Bai 3 Tim xhit- 2 (x+3)³ -x (3x+1)+ (2x+1). (4x²-20+1)=28 2 2 (x²-1)-(x²+x² + 1). (x² 1) = 0 (x2)–(x-3)–(x² + 3x+9) +6 (x+1)=49 bai & chickly mich quá tri men theng phu thus was hem (x+5)=(x-5) 20x+2 2 (x-1)-(x+1)² + 6. (x1)(x+4) 2 (3x+2). (9x²-6x+4)-9x=(3x²+1)+9x