We need to simplify the expression 36x² - 49 , but let's recall the identity which is the main key to solve this question i.e
- [tex]{\boxed{\bf{a^{2}-b^{2}=(a+b)(a-b)}}}[/tex]
So , here we can write the above expression as
[tex]{:\implies \quad \sf (6x)^{2}-(7)^{2}}[/tex]
Now , using the above identity this can be written as :
[tex]{:\implies \quad \sf (6x-7)(6x+7)}[/tex]
So , here both (6x-7) and (6x+7) are factors of 36x²- 49 , but in the options their is only 6x - 7.
Hence , Option D) 6x - 7 is correct
As here , 36x² = (6x)² = a² , so a = 6x and as 49² = 7² = b² , so b = 7
