ANSWER:
[tex]12x^4+12^3+26x^2+8x+12[/tex]
STEP-BY-STEP EXPLANATION:
We must calculate the area in each case and then do the subtraction, like this:
[tex]\begin{gathered} A=\mleft(3x^2+2\mright)\cdot\mleft(7x^2+4x+8\mright)=21x^4+12x^3+24x^2+14x^2+8x+16=21x^4+12x^3+38x^2+8x+16 \\ B=\mleft(3x^2+2\mright)^2=9x^4+12x^2+4 \end{gathered}[/tex]
The difference would be the following:
[tex]\begin{gathered} A-B=21x^4+12x^3+38x^2+8x+16-9x^4+12x^2+4 \\ A-B=12x^4+12^3+26x^2+8x+12 \end{gathered}[/tex]
