Find the 4th term from the beginning and end in the expansion of .
To Find :
I. 4th term from the beginning
II. 4th term from the end
Formulae :
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For ,
,
and n=9
As n=n ,therefore there will be total (n+1) terms in the expansion
Therefore,
I. For the 4th term from the starting.
We have a formula,
For t4 , r=3
Therefore, a 4th term from the starting
Now,
II. For the 4th term from the end
We have a formula,
For t(n-2) , r = (n-2)-1 = (n-3)
……….
Therefore, a 4th term from the end
Conclusion :
I. 4th term from the beginning
II. 4th term from the end