Given:
The objective is to find the difference between the polynomial equations (x^4+8x^3+9x^2)-(5x^4+4x^3+2x^2).
The difference can be calculated as,
[tex]\begin{gathered} =(x^4+8x^3+9x^2)-(5x^4+4x^3+2x^2) \\ =x^4+8x^3+9x^2-5x^4-4x^3-2x^2 \\ =x^4-5x^4+8x^3-4x^3+9x^2-2^2 \\ =-4x^4+4x^3+7x^2 \end{gathered}[/tex]Hence, option (d) is the correct answer.