document.write( "Question 867124: Sum ofthe series 21+22+23......200 \n" ); document.write( "
Algebra.Com's Answer #522739 by richwmiller(17219)\"\" \"About 
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an = a + (n - 1)d
\n" ); document.write( "200 = 21 + (n - 1)1
\n" ); document.write( "n=180
\n" ); document.write( "S = ½(a + an)n
\n" ); document.write( "S = ½(21 + 200)180
\n" ); document.write( "S = 19890
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