Solution
We are required to factorize
[tex]36(a^2-b^3)^4-18(a^2-b^3)^7[/tex][tex]=18(a^2-b^3)^4\text{ is a common factor}[/tex][tex]\begin{gathered} Thus,\text{ we have } \\ =18(a^2-b^3)^4(2-(a^2-b^3)^3) \end{gathered}[/tex][tex]\begin{gathered} Expand\text{ \lparen2-\lparen a}^2-b^2))^3 \\ =(2-a^6+3a^4b^3-3a^2b^6+b^9) \end{gathered}[/tex]Thus, the answer is