(x+1x)N
If the fifth term in this expansion is independant of X, find the value of N
(x+1x)N=xN+NxN−1x−1+N(N−1)2!xN−2x−2+...
The fifth term will therefore contain xN-4x-4 or xN-8. For this to be independent of x we must have N - 8 = 0 or N = 8
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