Question

n
y
29. Show that ay, Q7,..., An.... form an AP where a
35.
is defined as below:
(i) an = 2n+5
(ii) an = 6-n
Also find the sum of first 15 terms in each case. 36.​

Answer 1

Step-by-step explanation:

a1= 2*1 +5 =7

A2= 2*2+5=9

A3= 2*3+5=11

d= 9-7=2

s15 =15/2(2*7+(15-1)2)

=15/2(14+28)

=15/2 x42

=15*21

=315

similarly find the answer of another one

Answer 2

Answer:

1.an=2n+5

A1=2(1)+5=7

A2=2(2)+5=9

A3=2(3)+5=11

common difference=2

therfore it is an AP

2.an=6-n

A1=6-1=5

A2=6-2=4

A3=6-3=3

common difference= -1

therefore it is an AP