NTA Abhyas JEE Main2020MathematicsSequences and SeriesPractice
The value of the expression ∑ r = 0 ∞ 1 2 r ∑ k = 0 ∞ 1 3 k ∑ P = 0 ∞ 2 3 P is
Options
- A1
- B2
- C1 2
- D4 3
Correct answer
A. 1
Step-by-step solution
∑ r = 0 ∞ 1 2 r = 1 + 1 2 + 1 2 2 . . . . ∞ = a 1 - r = 1 1 - 1 2 = 2 (Applying formula of the sum of infinite G.P.) Similarly, ∑ K = 0 ∞ 1 3 K = 1 1 - 1 3 = 3 2 & ∑ P = 0 ∞ 2 3 P = 1 1 - 2 3 = 3 Hence, the expression simplifies to 2 × 3 2 3 = 1