Question

If the nth term of an ap is (3+n)/4, then the sum of first 105 terms is,

Answer 1

Answer:

tn=(3+n)/4

t1=4/4=l

t2=5/4=I 1/4

d = 1/4

a=1

S105=105/2{2xl+(105-1) 1/4}

= 105/2{2+104x1/4}

= 105/2(2+26)

= 105/2x28=1470