AP EAMCET2012MathematicsBinomial Theorem
_ k=1 ^ _ r=0 ^k 1 3^k ( ^k C_r ) is equal to
Options
- A1 3
- B2 3
- C1
- D2
Correct answer
D. 2
Step-by-step solution
aligned & _ k=1 ^ _ r=0 ^k 1 3^k ( ^k C_r ) = & _ k=1 ^ 1 3^k ( ^k C₀+ ^k C₁+ ^k C₂+ + ^k C_k ) = & _ k=1 ^ 2^k 3^k = _ k=1 ^ ( 2 3 )^k = & 2 3 + ( 2 3 )^1+ = & 2 / 3 1- 2 3 ( common ratio = 2 3 ) = & 2 aligned