Question

the forth of an AP is 8, and the sum of the firth 12 terms is 126. find the AP.

Answer 1

Answer:

Step-by-step explanation:

a4 = 8 Let a be the starting number and d be the common difference.

S12 = 126 n=12

n/2 ( 2a + n-1 x d ) = 126

6 ( 2a + 11 d ) = 126

2a + 11d = 21 ..................................... i

a4 = 8

a + 3d = 8

a = 8-3d................. ii

In i

2 ( 8- 3d ) + 11d = 21  By ii

d= 1

In  ii

a + 3 = 8

a = 5

∴ The AP is 5,6,7,8,.....................................