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What is the value of (S_{28}+28)?
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Answer and explanation
Correct answer: 434
The sum of the first 28 natural numbers is \(S_{28}=\frac{28\times29}{2}=406\). Therefore, \(S_{28}+28=406+28=434\). Option 435 is \(S_{29}\), because 29—not 28—is added to 406. Exam tip: Use \(S_n=\frac{n(n+1)}{2}\), then add the separately given number carefully.
Frequently asked questions
What is the correct answer to this question?
434
Why is this the correct answer?
The sum of the first 28 natural numbers is \(S_{28}=\frac{28\times29}{2}=406\). Therefore, \(S_{28}+28=406+28=434\). Option 435 is \(S_{29}\), because 29—not 28—is added to 406. Exam tip: Use \(S_n=\frac{n(n+1)}{2}\), then add the separately given number carefully.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Sum of first n natural numbers.
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