Answer:
Option c [tex]4l^2-81[/tex]
Explanation:
As we have given in the question
[tex]Sum=(2l+9)\times(2l-9)[/tex]
So by using the formula
[tex](a-b) (a+b) = a^2+ab-ba-b^2[/tex]
So the equation will become
[tex](a+b)(a-b)=a^2-b^2[/tex]
So according to question, we have ,
a = 2l and b = 9
So,
[tex](2l+9)(2l-9)=(4l^2-81)[/tex]
And required Sum=[tex](4l^2-81)[/tex]
So the final answer of the question which is required is Sum=[tex](4l^2-81)[/tex]
