`C_(0)-(C_(1))/(2)+(C_(2))/(3)-……+(-1)^(n)(C_(n))/(n+1)=(1)/(n+1)`
यदि `(1+x)^(n)=C_(0)+C_(1)x+C_(2)x^(2)+…+C_(n)x^(n)` तो साबित कीजिए कि
`C_(0)-(C_(1))/(2)+(C_(2))/(3)-……+(-1)^(n)(C_(n))/(n+1)=(1)/(n+1)`
`C_(0)-(C_(1))/(2)+(C_(2))/(3)-……+(-1)^(n)(C_(n))/(n+1)=(1)/(n+1)`
दिया गया श्रेणी है : `C_(0)-(C_(1))/(2)+(C_(2))/(3)-…+(-1)^(n).(C_(n))/(n+1)`
r वाँ पद, `t_(r)=(-1)^(r-1)(“”^(n)C_(r-1))/(r)`
अब, `C_(0)-(C_(1))/(2)+(C_(2))/(3)-…+(-1)^(n).(C_(n))/(n+1)`
`=underset(r=1)overset(n+1)sum(-1)^(r-1).(“”^(n)C_(r-1))/(r)=underset(r=1)overset(n+1)sum(-1)^(r-1).(“”^(n+1)C_(r))/(n+1)” “[because (“”^(n)C_(r-1))/(r)=(“”^(n+1)C_(r))/(n+1)]`
`=(1)/(n+1)[“”^(n+1)C_(1)-“”^(n+1)C_(2)+””^(n+1)C_(3)-…+(-1)^(n).””^(n+1)C_(n+1)]`
`=(1)/(n+1)[-“”^(n+1)C_(0)+””^(n+1)C_(1)-“”^(n+1)C_(2).+””^(n+1)C_(3)-…+(-1)^(n).””^(n+1)C_(n+1)+””^(n+1)C_(0)]`
`=(1)/(n+1)[-{“”^(n+1)C_(0)-“”^(n+1)C_(1)+…+(-1)^(n+1).””^(n+1)C_(n+1)}+””^(n+1)C_(0)]`
`=(1)/(n+1)[-(1-1)^(n+1)+””^(n+1)C_(0)]=(1)/(n+1)`