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AP EAMCET · Maths · Binomial Theorem

The coefficient of \(x^4\) in the expansion of \(\left(1+x-x^2-x^3\right)^{11}\) is

  1. A 990
  2. B 220
  3. C − 220
  4. D − 385
Verified Solution

Answer & Solution

Correct Answer

(C) − 220

Step-by-step Solution

Detailed explanation

\[ \begin{array}{ll} & \left(1+x-x^2-x^3\right)^{11} \\ \Rightarrow & {\left[1(1+x)-x^2(1+x)\right]^{11}} \\ \Rightarrow & {\left[\left(1-x^2\right)(1+x)\right]^{11}} \\ \Rightarrow & {\left[(1-x)(1+x)^2\right]^{11}} \\ \Rightarrow & (1-x)^{11} \cdot(1+x)^{22} \end{array} \] The…