IXL - Write variable expressions for arithmetic sequences (Algebra 1 practice)

Write an expression to describe the sequence below. Use n to represent the position of a term in the sequence, where n = 1 for the first term.

2, 3, 4, 5, ...

an =

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question

Write an expression to describe the sequence below. Use n to represent the position of a term in the sequence, where n = 1 for the first term.

5, 6, 7, 8, ...

an =

solution

The sequence 5, 6, 7, 8, ... looks like 1, 2, 3, 4, ... except each term is 4 larger. So, the expression that describes the sequence is n + 4. Check the first four terms:

To find the 1^st term, plug in n = 1.

n + 4 = 1 + 4 = 5

To find the 2^nd term, plug in n = 2.

n + 4 = 2 + 4 = 6

To find the 3^rd term, plug in n = 3.

n + 4 = 3 + 4 = 7

To find the 4^th term, plug in n = 4.

n + 4 = 4 + 4 = 8

The sequence 5, 6, 7, 8, ... is described by the expression n + 4.

Looking for more? Try these:

Lesson: Arithmetic sequences

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Not feeling ready yet? These can help:

U.4Evaluate variable expressions for number sequences

L.7Slope-intercept form: write an equation from a table

Lesson: Arithmetic sequences

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