document.write( "Question 1106491: In the arithmetic series, if S_n = 5n^2+4n, find the first three terms.\r
\n" ); document.write( "\n" ); document.write( "So the first term is 9, and I tried using the formula S_n= (a1+an)/2 * n\r
\n" ); document.write( "\n" ); document.write( "I got confused... does an = 5n^2+4n \n" ); document.write( "

Algebra.Com's Answer #721480 by ikleyn(52788) $\"\"$ $\"About$

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document.write( "    The first term is  = 9 with n = 1.\r\n" );
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document.write( "    The second term is  -  = 28-9 = 19.\r\n" );
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document.write( "    The third  term is  -  = 57-28 = 29.\r\n" );
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document.write( "That is all you need. The first three terms are 9, 19 and 29.\r\n" );
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\n" ); document.write( "On arithmetic progressions, see introductory lessons in this site:\r
\n" ); document.write( "\n" ); document.write( "    - Arithmetic progressions\r
\n" ); document.write( "\n" ); document.write( "    - The proofs of the formulas for arithmetic progressions \r
\n" ); document.write( "\n" ); document.write( "    - Problems on arithmetic progressions \r
\n" ); document.write( "\n" ); document.write( "    - Word problems on arithmetic progressions\r
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\n" ); document.write( "\n" ); document.write( "Also, you have this free of charge online textbook in ALGEBRA-II in this site\r
\n" ); document.write( "\n" ); document.write( "    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this online textbook under the topic \"Arithmetic progressions\".\r
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\n" ); document.write( "\n" ); document.write( "Save the link to this textbook together with its description\r
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\n" ); document.write( "\n" ); document.write( "Free of charge online textbook in ALGEBRA-II
\n" ); document.write( "https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson\r
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\n" ); document.write( "\n" ); document.write( "into your archive and use when it is needed.\r
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