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TS EAMCET · Maths · Binomial Theorem

The binomial expansion \((7+3 x)^{-2 / 5}\) is valid for all \(x\) in the interval \(\left(\frac{-7}{3}, \frac{7}{3}\right)\) and if the 4 th term of its expansion is \(k x^3\), then \(\left(7^{12 / 5} k\right)=\)

  1. A \(\frac{-2}{125}\)
  2. B \(\frac{-108}{125}\)
  3. C \(\frac{-72}{125}\)
  4. D \(-\frac{36}{125}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\frac{-108}{125}\)

Step-by-step Solution

Detailed explanation

We have, \((7+3 x)^{-2 / 5}=7^{-2 / 5}\left(1+\frac{3}{7} x\right)^{-2 / 5}\) 4th term of expansion is…