{"id":1679,"date":"2025-07-25T19:11:58","date_gmt":"2025-07-25T19:11:58","guid":{"rendered":"https:\/\/content.one.lumenlearning.com\/precalculus\/?post_type=chapter&p=1679"},"modified":"2026-03-25T21:45:17","modified_gmt":"2026-03-25T21:45:17","slug":"arithmetic-sequences-learn-it-2","status":"publish","type":"chapter","link":"https:\/\/content.one.lumenlearning.com\/precalculus\/chapter\/arithmetic-sequences-learn-it-2\/","title":{"raw":"Arithmetic Sequences: Learn It 2","rendered":"Arithmetic Sequences: Learn It 2"},"content":{"raw":"

Writing Terms of Arithmetic Sequences<\/h2>\r\nPreviously, we found a formula for the general term of a sequence, we can also find a formula for the general term of an arithmetic sequence.\r\n\r\nLet\u2019s write the first few terms of a sequence where the first term is [latex]a_1[\/latex] and the common difference [latex]d[\/latex]. We will then look for a pattern.\r\n\r\n\"A\r\n\r\nDid you notice that the number of [latex]d[\/latex]s that were added to [latex]a_1[\/latex] is one less than the number of the term?<\/span>\r\n\r\n
\r\n

general term (nth term) of an arithmetic sequence<\/h3>\r\nThe general term of an arithmetic sequence with first term [latex]a_1[\/latex] and the common difference [latex]d[\/latex] is\u00a0<\/span>\r\n

[latex]{a}_{n}={a}_{1}+\\left(n - 1\\right)d[\/latex]<\/p>\r\n\r\n<\/section>

Write the first five terms of the arithmetic sequence<\/strong> with [latex]{a}_{1}=17[\/latex] and [latex]d=-3[\/latex].\r\n\r\n[reveal-answer q=\"654025\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"654025\"]\r\n\r\nAdding [latex]-3[\/latex] is the same as subtracting [latex]3[\/latex]. Beginning with the first term, subtract [latex]3[\/latex] from each term to find the next term.The first five terms are [latex]\\left\\{17,14,11,8,5\\right\\}[\/latex]\"Graph\r\n\r\nAnalysis of the Solution\r\n\r\n<\/strong>As expected, the graph of the sequence consists of points on a line.[\/hidden-answer]<\/section>
[ohm_question hide_question_numbers=1]321960[\/ohm_question]<\/section>
How To: Given any the first term and any other term in an arithmetic sequence, find a given term.<\/strong>\r\n
    \r\n \t
  1. Substitute the values given for [latex]{a}_{1},{a}_{n},n[\/latex] into the formula [latex]{a}_{n}={a}_{1}+\\left(n - 1\\right)d[\/latex] to solve for [latex]d[\/latex].<\/li>\r\n \t
  2. Find a given term by substituting the appropriate values for [latex]{a}_{1},n[\/latex], and [latex]d[\/latex] into the formula [latex]{a}_{n}={a}_{1}+\\left(n - 1\\right)d[\/latex].<\/li>\r\n<\/ol>\r\n<\/section>
    Given [latex]{a}_{1}=8[\/latex] and [latex]{a}_{4}=14[\/latex] , find [latex]{a}_{5}[\/latex] .[reveal-answer q=\"644479\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"644479\"]The sequence can be written in terms of the initial term [latex]8[\/latex] and the common difference [latex]d[\/latex] .\r\n

    [latex]\\left\\{8,8+d,8+2d,8+3d\\right\\}[\/latex]<\/p>\r\nWe know the fourth term equals [latex]14[\/latex]; we know the fourth term has the form [latex]{a}_{1}+3d=8+3d[\/latex] .\r\n\r\nWe can find the common difference [latex]d[\/latex] .\r\n

    [latex]\\begin{align}&{a}_{n}={a}_{1}+\\left(n - 1\\right)d \\\\ &{a}_{4}={a}_{1}+3d \\\\ &{a}_{4}=8+3d && \\text{Write the fourth term of the sequence in terms of } {a}_{1} \\text{ and } d. \\\\ &14=8+3d && \\text{Substitute } 14 \\text{ for } {a}_{4}. \\\\ &d=2 && \\text{Solve for the common difference}. \\end{align}[\/latex]<\/p>\r\nFind the fifth term by adding the common difference to the fourth term.\r\n

    [latex]{a}_{5}={a}_{4}+2=16[\/latex]<\/p>\r\nAnalysis of the Solution<\/strong>\r\n\r\nNotice that the common difference is added to the first term once to find the second term, twice to find the third term, three times to find the fourth term, and so on. The tenth term could be found by adding the common difference to the first term nine times or by using the equation [latex]{a}_{n}={a}_{1}+\\left(n - 1\\right)d[\/latex].\r\n\r\n[\/hidden-answer]\r\n\r\n<\/section>

    [ohm_question hide_question_numbers=1]321961[\/ohm_question]<\/section>","rendered":"

    Writing Terms of Arithmetic Sequences<\/h2>\n

    Previously, we found a formula for the general term of a sequence, we can also find a formula for the general term of an arithmetic sequence.<\/p>\n

    Let\u2019s write the first few terms of a sequence where the first term is [latex]a_1[\/latex] and the common difference [latex]d[\/latex]. We will then look for a pattern.<\/p>\n

    \"A<\/p>\n

    Did you notice that the number of [latex]d[\/latex]s that were added to [latex]a_1[\/latex] is one less than the number of the term?<\/span><\/p>\n

    \n

    general term (nth term) of an arithmetic sequence<\/h3>\n

    The general term of an arithmetic sequence with first term [latex]a_1[\/latex] and the common difference [latex]d[\/latex] is\u00a0<\/span><\/p>\n

    [latex]{a}_{n}={a}_{1}+\\left(n - 1\\right)d[\/latex]<\/p>\n<\/section>\n

    Write the first five terms of the arithmetic sequence<\/strong> with [latex]{a}_{1}=17[\/latex] and [latex]d=-3[\/latex].<\/p>\n