document.write( "Question 775076: Write a rule for the nth turn of the arithmetic sequence. Then find a(20).
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Algebra.Com's Answer #472633 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "To get the 2nd term 4, you add 3 to the 1st term 1 time\r\n" );
document.write( "To get the 3rd term 7, you add 3 to the 1st term 2 times\r\n" );
document.write( "To get the 4th term 10, you add 3 to the 1st term 3 times.\r\n" );
document.write( "To get the 5th term 13, you add 3 to the 1st term 4 times.\r\n" );
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document.write( "To get the nth term an, you add 3 to the 1st term (n-1) times.\r\n" );
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document.write( "an = a1 + (n-1)·d\r\n" );
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document.write( "Substitute a1 = first term = 1 and d = 3 (the common\r\n" );
document.write( "difference between any term and the one before it.\r\n" );
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document.write( "an = 1 + (n-1)·3 = 1 + 3(n-1) = 1 + 3n - 3 = 3n-2.\r\n" );
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document.write( "an = 3n-2\r\n" );
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document.write( "Substitute n=20:\r\n" );
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document.write( "a20 = 3(20)-2 = 60-2 = 58. \r\n" );
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document.write( "Checking:\r\n" );
document.write( "1,4,7,10,13,16,19,22,25,28,31,34,37,40,43,46,49,52,55,58\r\n" );
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document.write( "Edwin
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