Question

(b) a = 7 और a13 = 35 दिया है। d और S1 ज्ञात करें।​

Answer 1

S1 = a1 = 7

a13 = a+12d

35 = 7 +12d

d= 28/12

d= 7/3

Answer 2

Answer:

d = 7/3, Sn=273

Step-by-step explanation:

First term of an AP = a = 7

Thirteenth term of an AP = 35

a + 12d = 35 ------(1)

Substitute a in eq - (1)

a + 12d = 35

(7) + 12d = 35

12d = 35 - 7

12d = 28

d = 28/12

d = 7/3

In an AP sum of the terms = n/2 ( a + an )

= 13/2 ( 7 + 35)

= 13/2 ( 42)

= 13(21)

= 273