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JEE Mains · Maths · STD 11 - 7. binomial theoram

If the term independent of \(x\) in the exapansion of \(\left(\frac{3}{2} x^{2}-\frac{1}{3 x}\right)^{9}\) is \(k,\) then \(18 k\) is equal to

  1. A \(9\)
  2. B \(11\)
  3. C \(5\)
  4. D \(7\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(7\)

Step-by-step Solution

Detailed explanation

\(T _{ r +1}={ }^{9} C _{ r }\left(\frac{3}{2} x ^{2}\right)^{9- r }\left(-\frac{1}{3 x }\right)^{ r }\) \(T _{ r +1}={ }^{9} C _{ r }\left(\frac{3}{2}\right)^{9- r }\left(-\frac{1}{3}\right)^{ r } x ^{18-3 r }\) For independent of x \(18-3 r=0, r=6\)…