document.write( "Question 860618: The sum of the first seven terms of an AP is 98 and the sum of the first twelve terms is 288.Find the sum of the first twenty terms. \n" ); document.write( "

Algebra.Com's Answer #518544 by ewatrrr(24785) $\"\"$ $\"About$

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document.write( "6(2a + 11d) = 288
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document.write( "7(2a + 6d = 196 
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document.write( "    2a + 11d = 48
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document.write( "    2a + 6d = 28
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document.write( "           5d = 20
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document.write( "            d = 4  and a = 2 
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document.write( " = 800
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