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The coefficients of (r-1)^(t h),\ r t h\...

The coefficients of `(r-1)^(t h),\ r t h\ a n d\ (r+1)^(t h)` terms in the expansion of `(x+1)^n` are in the ratio 1:3:5. Find `n\ a n d\ rdot`

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Coefficient of `(r-1)` th term `=C(n, r-2)`
Coefficient of rth term `=C(n, r-1)`
Coefficient of `(r+1)` th term `=C(n, r)`
C(n, r-2): C(n, r-1): C(n, r)=1: 3: 5
...
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