Question

Show that a1, a2, a3..........an,......form an AP where an is defined as an = 3 + 4n Also find the sum of

first 10 terms.​

Answer 1

Answer:

an = 3 + 4n

n = 1

a1 = 3 + 4 = 7

n = 2

a2 = 3 + 8 = 11

n = 3

a3 = 3 + 12 = 15

d = a2 - a1 = a3 - a2

d = 11 - 7 = 15 -11

d = 4 = 4

Hence it forms an AP.

S10 = 10/2( 2*7 + 9*4 )

S10 = 5( 14 + 36 )

S10 = 250