If the third term of the arithmetic progression (x, x + 6, x + 12, …) is 25, what is x?
Answer and explanation
Correct answer: 13
The governing concept is identifying the position of a term in an explicitly written sequence. The listed terms are first x, second x + 6, and third x + 12. Since the third term is given as 25, set x + 12 = 25. Subtracting 12 from both sides gives x = 13. Substitution verifies the sequence as 13, 19, 25, …, whose third term is indeed 25 and whose common difference is 6. Option A would make the third term 23, option C would make it 27, and option D would make it 29. Therefore, option B is the only value satisfying the condition.
Frequently asked questions
What is the correct answer to this question?
13
Why is this the correct answer?
The governing concept is identifying the position of a term in an explicitly written sequence. The listed terms are first x, second x + 6, and third x + 12. Since the third term is given as 25, set x + 12 = 25. Subtracting 12 from both sides gives x = 13. Substitution verifies the sequence as 13, 19, 25, …, whose third term is indeed 25 and whose common difference is 6. Option A would make the third term 23, option C would make it 27, and option D would make it 29. Therefore, option B is the only value satisfying the condition.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Explicit or general rule.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
