If `x^4`occurs in the rth term in the expansion of `(x^4+1/(x^3))^(15),`then find the value of `rdot`A. 4B. 8C. 9D. 10

If `x^4`occurs in the rth term in the expansion of `(x^4+1/(x^3))^(15)

1.	If `x^4`occurs in the rth term in the expansion of `(x^4+1/(x^3))^(15),`then find the value of `rdot`A. 4B. 8C. 9D. 10
Answer» Correct Answer - C In the expansion of `(x^(4)+(1)/(x^(3)))^(15)`, let `T_(r)` is the `n_(th)` term `T_(r)=""^(15)C_(r-1)(x^(4))^(15-r+1)((1)/(x^(3)))^(r-1)` `=15_(C_(r-1))x^(64-4r-3r+3)=15_(C_(r-1))x^(67-7r)` `x^(4)` occurs in this term `rArr" "4=67-7r` `rArr" "7r=63` `rArr" "r=9.`

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