document.write( "Question 1187235: The first three terms of a geometric progression are k + 15,k and k - 12 respectively, find the value of k and the sum to infinity. \n" ); document.write( "

Algebra.Com's Answer #818181 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "The first three terms of a geometric progression are k + 15,k and k - 12 respectively,
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document.write( "Since the first three terms of a geometric progression are k + 15,k and k - 12 respectively, \r\n" );
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document.write( "we have this proportion\r\n" );
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document.write( "     = .\r\n" );
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document.write( "Cross multiply, simplify and find k\r\n" );
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document.write( "    (k-12)*(k+15) = k^2\r\n" );
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document.write( "     k^2 - 12k + 15k - 180 = k^2\r\n" );
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document.write( "           3k              = 180\r\n" );
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document.write( "            k              = 180/3 = 60.\r\n" );
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document.write( "The first three terms are  75, 60, 48.\r\n" );
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document.write( "The common dofference is  r =  =  = 0.8.\r\n" );
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document.write( "The sum to infinity is  S =  =  =  = 375.\r\n" );
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