CBSE
Gujarat Board
Haryana Board
Class 10
Class 12
23
13
19
49
D.
Let fx = ax∑x = 1∞ fx = 2⇒ a + a2 +a3 ... ∞ terms = 2⇒ a1 - a = 2 ⇒ a = 23⇒ fx = 23xNow, f4f2 = 234232 = 49