document.write( "Question 118821: In the geometric sequence the first three terms are ( 5x-8,3x,2x+2,...).What is the value of x ? Please help me :) \n" ); document.write( "
Algebra.Com's Answer #86942 by Earlsdon(6294)\"\" \"About 
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Find the value of x if the first three terms of a geometric sequence are given as:
\n" ); document.write( "{5x-8, 3x, 2x+2,...}
\n" ); document.write( "You know that in a geometric sequence, consecutive terms have a common ratio.
\n" ); document.write( "This can be expressed as:
\n" ); document.write( "\"a%5Bn%5D%2Fa%5Bn-1%5D++=+k\" or, in words...Any term divided by the previous term is a constant called the common ratio, r.
\n" ); document.write( "So, let's use this useful fact to find x in your problem:
\n" ); document.write( "\"3x%2F%285x-8%29+=+k\" and...
\n" ); document.write( "\"%282x%2B2%29%2F3x+=+k\" and, since k = k, we can set these two equal to each other:
\n" ); document.write( "\"3x%2F%285x-8%29+=+%282x%2B2%29%2F3x\" Simplify and solve for x.
\n" ); document.write( "\"3x%283x%29+=+%285x-8%29%282x%2B2%29\" Expand.
\n" ); document.write( "\"9x%5E2+=+10x%5E2-6x-16\" Subtract \"9x%5E2\" from both sides.
\n" ); document.write( "\"0+=+x%5E2-6x-16\"Solve this quadratic equation by factoring.
\n" ); document.write( "\"%28x%2B2%29%28x-8%29+=+0\" Apply the zero product principle:
\n" ); document.write( "\"x%2B2+=+0\" or \"x-8+=+0\"
\n" ); document.write( "If \"x%2B2+=+0\" then \"x+=+-2\" or
\n" ); document.write( "if \"x-8+=+0\" then \"x+=+8\"
\n" ); document.write( "So there are two possible solutions for x.
\n" ); document.write( "\"x+=+-2\"or \"x+=+8\" and since the problem does not give us the common ratio, both values of x are valid solutions.
\n" ); document.write( "Check:
\n" ); document.write( "{5x-8, 3x, 2x+2,...} Let's try x = -2
\n" ); document.write( "{5(-2)-8, 3(-2), 2(-2)+2,...}
\n" ); document.write( "{-18, -6, -2,...} The common ratio, r, is:
\n" ); document.write( "\"-6%2F-18+=+1%2F3\"
\n" ); document.write( "\"-2%2F-6+=+1%2F3\" OK
\n" ); document.write( "Now try x = 8:
\n" ); document.write( "{5x-8, 3x, 2x+2,...}
\n" ); document.write( "{5(8)-8, 3(8), 2(8)+2,...}
\n" ); document.write( "{32, 24, 18,...} The common ratio here is:
\n" ); document.write( "\"24%2F32+=+3%2F4\"
\n" ); document.write( "\"18%2F24+=+3%2F4\" OK
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