Question

If sum of n terms of an AP is n²+8n, then find the common difference of the AP

Answer 1

Answer:

2

Step-by-step explanation:

Sn = n² + 8n (Given)

STEP 1: Find the sum of 1 term

When n = 1

s1 = (1)²  + 8(1)

s1 = 9

STEP 2: Find the 1st term

a1 = s1

a1 = 9

STEP 3: Find the sum of first 2 terms

When n = 2

s2 = (2)² + 8(2)

s2 = 20

STEP 4: Find the 2nd term

s2 = a1 + a2

20 = 9 + a2

a2 = 20 - 9

a2 = 11

STEP 5: Find the common difference:

Common Difference = a2 - a1

Common Difference = 11 - 9

Common Difference = 2

Answer: 2