If the 6 th term in $\left(\frac{2 p}{3}+\frac{3 q}{2}\right)^9$ is " $a p^b q^{c \prime}$, then $a, b$ and…

If the 6 th term in $\left(\frac{2 p}{3}+\frac{3 q}{2}\right)^9$ is " $a p^b q^{c \prime}$, then $a, b$ and $c$ respectively are
  1. $189,5,4$
  2. $189,4,5$
  3. $212,4,5$
  4. $212,5,4$

Solution

The sixth term in the expansion $\left(\frac{2 p}{3}+\frac{3 q}{2}\right)^9$ is $ \begin{aligned} T_6 & =T_{5+1}={ }^9 C_5\left(\frac{2 p}{3}\right)^4\left(\frac{3 q}{2}\right)^5 \\ & =\frac{9 \times 8 \times 7 \times 6}{4 \times 3 \times 2} \times\left(\frac{2}{3}\right)^4\left(\frac{3}{2}\right)^5 p^4 q^5 \\ & =189 p^4 q^5=a p^b q^c \end{aligned} $ (given) On comparing, we get $ a=189, b=4 \text { and } c=5 $

Asked in: AP EAMCET 2020 (22 Sep Shift 1)

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