1.

Consider the expansion `(x^(2)+(1)/(x))^(15)`. What is the independent term in the given expansion ?A. 2103B. 3003C. 4503D. None of these

Answer» Correct Answer - B
`(x^(2)+(1)/(x))^(15)`
`T_(r+1)=.^(15)C_(r)(x^(2))^(15-r)((1)/(x))^(r)`
`=.^(15)C_(r)x^(30-2r-r)=.^(15)C_(r)x^(30-3r)`
For independent term,
`30 - 3r = 0 rArr r = 10`
Put r = 10, we get
`T_(10+1)=.^(15)C_(10)=(15!)/(10!5!)`
`=(15 xx 14 xx 13 xx 12 xx 11 xx 10!)/(10! xx 1 xx 2 xx 3 xx 4 xx 5)=3003`


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