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  • If the Kth term of the binomial theorem <img alt="\left ( x+y \right )^{20}\: \: is\: \: Ax^3y^r" src="http://entrancecorner.oncodecogs.com/gif.latex?%5Cleft%20%28%20x&plus;y%20%5Cright%20

If the Kth term of the binomial theorem \left ( x+y \right )^{20}\: \: is\: \: Ax^3y^r. Find r.

Option: 1

3


Option: 2

20


Option: 3

17


Option: 4

0


Answers (1)

best_answer

As we learnt

In the expression of \left ( x+a \right )^{n}, the sum of the power of x and a in each term is equal to n .

 

Now,

Kth term of the binomial theorem \left ( x+y \right )^{20}\: \: is\: \: Ax^3y^r

Now, sum of powers of x and y must be 20

Thus r + 3 = 20

\Rightarrow r = 17

Posted by

Ajit Kumar Dubey

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