document.write( "Question 1019525: in a certain ap the 32nd term is twice the 12th term prove that 70th term is twice the 31st term
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Algebra.Com's Answer #635483 by robertb(5830)\"\" \"About 
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The usual formula for the nth term of an AP is \"a%5Bn%5D+=+a%5B1%5D+%2B+%28n-1%29d\". For the purpose of proving the statement, we use the alternative formula \r
\n" ); document.write( "\n" ); document.write( "\"a%5Bn%5D+=+a%5Bk%5D+%2B+%28n-k%29d\", where k = 1, 2, 3, ...., n-1.\r
\n" ); document.write( "\n" ); document.write( "We are also given that \"a%5B32%5D+=+2a%5B12%5D\"\r
\n" ); document.write( "\n" ); document.write( "Using this formula,\r
\n" ); document.write( "\n" ); document.write( "\"a%5B70%5D+=+a%5B32%5D%2B38d+=+2a%5B12%5D+%2B38d+=+2%28a%5B12%5D%2B19d%29+=+2a%5B31%5D\",\r
\n" ); document.write( "\n" ); document.write( "and the statement is proved.
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