Question

12. 7, 14, 21, 28. . . . . . . . . . . . . . How many posts are the sum of 952 in​

Answer 1

Answer:

16th terms are there in A.P. [Arithmetic Progression]

Step-by-step explanation:

• aₙ = a + (n - 1)d
• Sₙ = n/2[a + l]

(l stands for value of aₙ)

1. S = 952
2. S = 952a = 7
3. S = 952a = 7d = 7

→ aₙ = 7 + (n - 1)7

→ aₙ = 7 + 7n - 7

→ aₙ = 7n

→ Sₙ = n/2[7 + 7n]

→ 952 × 2 = 7n + 7n²

→ 7n² + 7n - 1904 = 0

• D = b² - 4ac

D = 49 - 4(7)(- 1904)

D = 53361

Now, n = (- b ± √D)/2a

Case 1: n = (- 7 + 231)/2(7)

→ n = 16

Case 2: n = (- 7 - 231)/2(7)

→ n = - 17

Since number terms can't be in negative therefore n = 16