Question:medium

The 20th term of the sequence 1, 4, 7, 10, ... is equal to

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Use $a_n = a + (n-1)d$ directly for nth term of an A.P.
Updated On: Feb 27, 2026
  • 56
  • 66
  • 68
  • 58
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The Correct Option is D

Solution and Explanation

To find the 20th term of the sequence 1, 4, 7, 10, ..., we first need to identify the type of sequence given.

This sequence is an arithmetic sequence since the difference between consecutive terms is constant.

The common difference (\(d\)) can be calculated as:

\(d = 4 - 1 = 3\)

The first term (\(a\)) of the sequence is 1.

The formula for the \(n\)th term (\(T_n\)) of an arithmetic sequence is: \(T_n = a + (n-1) \cdot d\)

Substituting the values for \(a\), \(d\), and \(n = 20\):

\(T_{20} = 1 + (20-1) \cdot 3\)

\(T_{20} = 1 + 19 \cdot 3\)

\(T_{20} = 1 + 57\)

\(T_{20} = 58\)

Therefore, the 20th term of the sequence is 58.

This matches the correct answer.

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