document.write( "Question 1132681: The first term of an arithmetic progression is -8.The ratio of the 7th term to the 9th is 5:8. Calculate the common difference \n" ); document.write( "

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\n" ); document.write( "The first term of an arithmetic progression is -8.The ratio of the 7th term to the 9th is 5:8. Calculate the common difference
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document.write( "We then get: 
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document.write( "8(- 8 + 6d) = 5(- 8 + 8d) ------- Cross-multiplying
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document.write( "- 64 + 48d = - 40 + 40d
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document.write( "48d - 40d = - 40 + 64
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document.write( "8d = 24
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document.write( "d, or common difference =  \n" );
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