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TS EAMCET · Maths · Binomial Theorem

The coefficient of \(x^3 y^4 z^5\) in the expansion of \((x y+y z+x z)^6\) is

  1. A 70
  2. B 60
  3. C 50
  4. D None of these
Verified Solution

Answer & Solution

Correct Answer

(B) 60

Step-by-step Solution

Detailed explanation

We have \(\begin{aligned} (x y+y z+z x)^6 & =\sum_{r+s+t=6} \frac{6 !}{r ! s ! t !}(x y)^r(y z)^s(z x)^t \\ & =\sum_{r+s+t=6} \frac{6 !}{r ! s ! t !} x^{r+t} y^{r+s} z^{s+t} \end{aligned}\) If the general term in the above expansion. contains \(x^3 y^4 z^5\), then…