Question

How many terms are there in the A.P. 9, 13, 17, 21, ................. 97 ?​

Answer 1

Answer:

12 terms are there .............

Answer 2

Answer:

• 23 terms

Step-by-step explanation:

Given

• Progression : 13 , 17 , 21 , .. , 97

To find

• How many terms are there

Solution

➔ nₜₕ term of an AP = a + (n - 1)d

Where:

• a = first term
• d = common difference
• n = term

Here:

• a = 9
• d = (13 - 9)
• d = 4

Substituting we get:

• Tₙ = 97 = a + (n - 1)d = 97
• 9 + (n - 1)4 = 97
• (n - 1)4 = 97 - 9 = 88
• (n - 1) = ⁸⁸⁄₄ = 22
• n = 22 + 1
• n = 23

Hence, the given AP contains 23 terms.