Question

Find the sum of the 1st 112 terms of: 7 + 11 +15 + .....
25648
112
224
25846

Answer 1

It is an Ap (Arithmetic Sequence)

d=4

a=7

n=112

Using the Formula

Sn= n/2[2a + (n-1)d]

Sn= 112/2 [2(7) + (112-1)(4)]

Sn= 56[14 + (111)(4)]

Sn= 56[14 + 444]

Sn= 56(458)

Sn= 25,648.