JEE Mains · Maths · STD 11 - 7. binomial theoram
If the coefficients of the middle terms in the binomial expansions of \((1 + \alpha x)^{26}\) and \((1 - \alpha x)^{28}\), \(\alpha \neq 0\), are equal, then the value of \(\alpha\) is:
- A \(1\)
- B \(\dfrac{14}{13}\)
- C \(\dfrac{27}{7}\)
- D \(\dfrac{7}{27}\)
Answer & Solution
Correct Answer
(D) \(\dfrac{7}{27}\)
Step-by-step Solution
Detailed explanation
The expansion of \((1 + \alpha x)^{26}\) has \(27\) terms. The middle term is \(T_{14}\). The coefficient of the middle term is \(^{26}C_{13} \alpha^{13}\). The expansion of \((1 - \alpha x)^{28}\) has \(29\) terms. The middle term is \(T_{15}\). The coefficient of the middle…
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