What is the sum of the first (4) terms of the sequence (3,9,27,81,\ldots)?
Answer and explanation
Correct answer: 120
The first four terms are 3, 9, 27, and 81. Therefore, their sum is \(3+9+27+81=120\). This is also a geometric sequence, since each term is 3 times the previous term. Option 114 is incorrect because it is less than the actual total of the four given terms. Exam tip: when only a few terms are given, list them and add directly to avoid mistakes.
Frequently asked questions
What is the correct answer to this question?
120
Why is this the correct answer?
The first four terms are 3, 9, 27, and 81. Therefore, their sum is \(3+9+27+81=120\). This is also a geometric sequence, since each term is 3 times the previous term. Option 114 is incorrect because it is less than the actual total of the four given terms. Exam tip: when only a few terms are given, list them and add directly to avoid mistakes.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Sequences.
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