The value of x for which the equation $$\sqrt{4x - 9}$$ + $$\sqrt{4x + 9}$$ = 5 + $$\sqrt{7}$$ will be satisfied, is:

This question can be solved with the help of options easily. 
We can say that 4x - 9 $$\geq$$ 0. Hence x $$\geq$$ 2.25. Now we can check option C and D.

Option C: $$\sqrt{4x - 9}$$ + $$\sqrt{4x + 9}$$ = $$\sqrt{3}$$ + $$\sqrt{21}$$ Which is not same as what we have in the question. Hence, this is not the correct answer. 

Option D: $$\sqrt{4x - 9}$$ + $$\sqrt{4x + 9}$$ = $$\sqrt{7}$$ + $$\sqrt{25}$$ = 5 + $$\sqrt{7}$$. Which is the same as what we have in the question. Hence, we can say that option D the correct answer.