document.write( "Question 1153525: The second, fourth and eight terms of an A.P are in geometrical progression and the sum of the third and fifth term is 20. Find the first four terms of the progression. \n" ); document.write( "

Algebra.Com's Answer #775769 by MathLover1(20850) $\"\"$ $\"About$

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\n" ); document.write( "AP:
\n" ); document.write( "2nd term: $\"a+%2B+d\"$ ,
\n" ); document.write( "4th term: $\"a+%2B+3d\"$ ,
\n" ); document.write( "8th term: $\"a+%2B+7d\"$ \r
\n" ); document.write( "\n" ); document.write( " These $\"3\"$ terms are in GP: \r
\n" ); document.write( "\n" ); document.write( " $\"+++%28a+%2B+d%29%28a+%2B+7d%29++-%28a+%2B+3d%29%5E2+=0\"$
\n" ); document.write( " $\"a%5E2+%2B+8+a+d+%2B+7+d%5E2-%28a%5E2+%2B+6+a+d+%2B+9+d%5E2%29=0\"$
\n" ); document.write( " $\"a%5E2+%2B+8+a+d+%2B+7+d%5E2-a%5E2+-+6+a+d+-+9+d%5E2=0\"$
\n" ); document.write( " $\"+2a+d++-+2+d%5E2=0\"$
\n" ); document.write( " $\"2d%28a+-+d%29+=+0\"$
\n" ); document.write( " $\"2ad+-+2d%5E2=0+\"$
\n" ); document.write( " $\"2ad+=2d%5E2+\"$
\n" ); document.write( " $\"a+=+d\"$ \r
\n" ); document.write( "
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\n" ); document.write( "\n" ); document.write( "Sum of 3rd and 5th terms is:
\n" ); document.write( "
\n" ); document.write( " $\"%28a+%2B+2d%29+%2B+%28a+%2B+4d%29+=20\"$
\n" ); document.write( " $\"2a+%2B+6d+=+20\"$
\n" ); document.write( " $\"++8d+=+20\"$
\n" ); document.write( " $\"d+=+2.5\"$ or $\"d=%285%2F2%29\"$ \r
\n" ); document.write( "\n" ); document.write( "=> $\"+a+=+2.5\"$ or $\"%285%2F2%29\"$ \r
\n" ); document.write( "\n" ); document.write( " AP:
\n" ); document.write( "1st term: $\"2.5\"$
\n" ); document.write( "2nd term: $\"5\"$
\n" ); document.write( "3rdterm: $\"7.5\"$
\n" ); document.write( "4th term: $\"10\"$
\n" ); document.write( "5thterm: $\"12.5\"$
\n" ); document.write( "8th term: $\"20\"$ \r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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