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If (r+1)t h term is the first negative t...

If `(r+1)t h` term is the first negative term in the expansion of `(1+x)^(7//2),` then find the value of `rdot`

Text Solution

Verified by Experts

The correct Answer is:
`r = 5`
We have
`T_(r+1) = (7/2(7/2-1)(7/2-2)"….."(7/2-r+1)x^(r))/(r!)`
This will be the first negative term when
`7/2 - r+1lt0`, i.e, `r gt 9/2`
Hence, `r = 5`.
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