document.write( "Question 1151377: The third term of a geometric progression is nine times the first term.The sum of the first four terms is K times the first term. Find the values of possible values of K. \n" ); document.write( "

Algebra.Com's Answer #773120 by ikleyn(52835) $\"\"$ $\"About$

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document.write( "We are given \r\n" );
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document.write( "     =  = .\r\n" );
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document.write( "It implies   = 9;  hence, taking the square root of both sides,\r\n" );
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document.write( "we have TWO possible values for the common ratio \"r\"  :  r = 3  or  r = -3.\r\n" );
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document.write( "If r= 3, then the sum of the first four terms is   =  = .\r\n" );
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document.write( "    Hence, in this case  K = 40.\r\n" );
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document.write( "If r= -3, then the sum of the first four terms is   =  = .\r\n" );
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document.write( "    Hence, in this case  K = -20.\r\n" );
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document.write( "ANSWER.  Two values are possible for K:  40 and - 20.\r\n" );
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