document.write( "Question 859437: please help to solve the following\r
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document.write( "the sum of the first and the third terms of a geometric progression is 40. the sum of the second and the fourth terms is 120. Determine the first term and the common ratio of the progression. \n" );
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Algebra.Com's Answer #517751 by mananth(16946)![]() ![]() You can put this solution on YOUR website! the terms will be \n" ); document.write( "a,ar,ar^2,ar^3\r \n" ); document.write( "\n" ); document.write( "Condition I\r \n" ); document.write( "\n" ); document.write( "a+ar^2=40 \n" ); document.write( "a*(1+r^2)=40 \n" ); document.write( "(1+r^2) =40/a\r \n" ); document.write( "\n" ); document.write( "condition II\r \n" ); document.write( "\n" ); document.write( "ar+ar^3=120\r \n" ); document.write( "\n" ); document.write( "ar(1+r^2)=120\r \n" ); document.write( "\n" ); document.write( "ar(40/a) =120\r \n" ); document.write( "\n" ); document.write( "40r =120\r \n" ); document.write( "\n" ); document.write( "r=3\r \n" ); document.write( "\n" ); document.write( "plug r to get a \n" ); document.write( " |