Answer:
9a^4b^10 ( 4 - 9a^12b^20)
Explanation:
The greatest common factor of the two terms is 9a^4b^10
You can now remove the greatest common factor outside the brackets.
Inside the brackets, you place the value obtained by dividing 36a^4b^10- 81a^16b^20 by 9a^4b^10
That is = 4 - 9a^12b^20
Please note that the laws of indices i used for the above division is: n^a divided by n^b = n^(a-b)
Now, the factorised answer for your question = 9a^4b^10 ( 4 - 9a^12b^20)
Hope thos helps