What is the common difference in the sequence (3a,3a-4,3a-8,\ldots)?
Answer and explanation
Correct answer: -4
The common difference is found by subtracting a term from the term immediately after it. Here, \(d=(3a-4)-3a=-4\). Also, \((3a-8)-(3a-4)=-4\), confirming that the common difference is \(-4\). The number \(4\) is only the magnitude of the difference; for a decreasing AP, the common difference is negative. Exam tip: Write \(d=a_2-a_1\) and check the sign carefully.
Frequently asked questions
What is the correct answer to this question?
-4
Why is this the correct answer?
The common difference is found by subtracting a term from the term immediately after it. Here, \(d=(3a-4)-3a=-4\). Also, \((3a-8)-(3a-4)=-4\), confirming that the common difference is \(-4\). The number \(4\) is only the magnitude of the difference; for a decreasing AP, the common difference is negative. Exam tip: Write \(d=a_2-a_1\) and check the sign carefully.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Introduction to APs and common difference..
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
