If (a_n=n^2+3n), what is the value of (a_4)?
Answer and explanation
Correct answer: 28
Substitute 4 for n: \(a_4=4^2+3(4)=16+12=28\). Hence, 28 is correct. Getting 26 usually results from an error in calculating \(3\times4\) or in addition. Exam tip: To find a term from an explicit rule, replace every n with the given term number and simplify step by step.
Frequently asked questions
What is the correct answer to this question?
28
Why is this the correct answer?
Substitute 4 for n: \(a_4=4^2+3(4)=16+12=28\). Hence, 28 is correct. Getting 26 usually results from an error in calculating \(3\times4\) or in addition. Exam tip: To find a term from an explicit rule, replace every n with the given term number and simplify step by step.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Explicit or general rule.
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