4. ( x4 + ax2 + b ) chia hết cho ( x2 – 3x + 2
5. ( x4 – 3x3 – 3x2 + ax + b ) chia hết cho ( x2 – 3x + 4 )
6. (x4 + x3 – x2 + ax + b ) chia hết cho ( x2 + x – 2 )
7. ( ax4 + bx3 + 1 ) chia hết cho ( x – 1 )2
8. ( x3 + ax2 + 2x + b ) chia hết cho ( x2 + x + 1 )