JEE Mains · Maths · STD 11 - 7. binomial theoram
The sum of the coefficients of three consecutive terms in the binomial expansion of \((1+ x )^{ n +2}\), which are in the ratio \(1: 3: 5\), is equal to
- A \(25\)
- B \(63\)
- C \(41\)
- D \(92\)
Answer & Solution
Correct Answer
(B) \(63\)
Step-by-step Solution
Detailed explanation
\({ }^{n+2} C_{ r -1}:{ }^{n+2} C_{ r }:{ }^{ n +2} C _{ r +1}=1: 3: 5\) \(\frac{{ }^{n+2} C_{ r -1}}{{ }^{ n +2} C _{ r }}=\frac{1}{3}\) \(n =4 r -3 \ldots \ldots \text { (i) }\) \(\frac{{ }^{n+2} C _{ r }}{{ }^{ n +2} C _{ r +1}}=\frac{3}{5}\)…
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