ban coi co dung huong khong thi giai tiep nhavi x^3+1co mot nghiem don va vo nghiem nen ta co the tach thanh x/(x+1)(x^2-x+1)
tiep theo dung dong nhat thuc ta co A/(x+1)+(Bx+C)/(x^2-x+1)
quy dong giai he cua ba pt -A+B+C=1; A+B=0 ; A+C=0
Ta duoc A=-1/3; B=C=1/3
Nguyen ham tren tro thanh nguyen ham cua (-1/3)/(x+1) + nguyen ham cua (1/3x+1/3)/(x^2-x+1)
Toi day ban tu giai tiep di nha. Ket qua ... bam may tinh se ra.