document.write( "Question 839221: Three positive numbers are in the ratio 1:3:8. if 7 is added to the largest number the three numbers form a geometric sequence. Find the numbers. \n" ); document.write( "

Algebra.Com's Answer #506214 by Edwin McCravy(20059) $\"\"$ $\"About$

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document.write( "Since the numbers are in the ratio 1:3:8, then k:3k:8k where k is\r\n" );
document.write( "not zero, represents all triples of numbers in the ration 1:3:8\r\n" );
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document.write( "So let the three numbers be k,3k, and 8k\r\n" );
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document.write( "Then the terms k, 3k, and 8k+7 form a geometric sequence.\r\n" );
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document.write( "The common ratio =  = \r\n" );
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document.write( "Therefore   = \r\n" );
document.write( "            = \r\n" );
document.write( "Multiply through by 3k  \r\n" );
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document.write( "           9k = 8k+7\r\n" );
document.write( "            k = 7\r\n" );
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document.write( "Then the numbers are  k,3k, and 8k or 7,21,56\r\n" );
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document.write( "Checking: adding 7 to the 3rd term gives the sequence 7,21,63\r\n" );
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document.write( "That checks, since 7*3=21 and 21*3=63\r\n" );
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document.write( "Edwin

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