Question

If Tn=1/n(n+5) find Sn

Answer 1

Tn=1/n(n+5). -(1)

let n=1

=>T1=1/1(1+5)=6

therefore, T1=6

Similarly, Let n=2

=>T2=1/2(2+5)=7/2

T2-T1=common difference

d=7/2-6= -5/2

$sn = \frac{n}{2} (2a + (n - 1)d$

Therefore,

Sn={n/2(2×1)+(n-1)-5/2}

Sn=

$sn = \frac{9n - {5n}^{2} }{2}$

#Hence Solved#