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AP EAMCET · Maths · Binomial Theorem

The coefficient of \(x^2\) in the expansion of \((1-3 x)^{-1 / 4}\) is

  1. A \(\frac{45}{64}\)
  2. B \(\frac{45}{8}\)
  3. C \(\frac{45}{16}\)
  4. D \(\frac{45}{32}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{45}{32}\)

Step-by-step Solution

Detailed explanation

\begin{aligned} & \text { (d) }(1-3 x)^{-\frac{1}{4}} \\ & =1+\left(-\frac{1}{4}\right)(-3 x)+\frac{\left(-\frac{1}{4}\right)\left(-\frac{1}{4}-1\right)}{2 !}(-3 x)^2+\ldots \\ & =1+\frac{3}{4}+\frac{\left(\frac{1}{4}\right)\left(\frac{5}{4}\right)}{2 !}(9) x^2+\ldots \\ & \text…