document.write( "Question 1175621: A man buys premium bonds every year . In the first year , he buys sh.2000 worth of bonds . If every year he increases his annual investments in bonds by sh.600 , how long will he take for his total investment in bonds to be sh.37000 \n" ); document.write( "
Algebra.Com's Answer #801280 by Boreal(15235)\"\" \"About 
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a1=2000
\n" ); document.write( "a2=3200
\n" ); document.write( "an=2000+(n-1)600
\n" ); document.write( "sum=(n/2)(2a+(n-1)d)
\n" ); document.write( "37000=(n/2)(4000+(n-1)600)
\n" ); document.write( "74000=n(4000+600n-600))=3400n+600n^2
\n" ); document.write( "600n^2+3400n-74000=0
\n" ); document.write( "6n^2+34n-740=0
\n" ); document.write( "3n^2+17n-370=0\r
\n" ); document.write( "\n" ); document.write( "n=(1/6)(-17+ sqrt (4729)); sqrt term=68.76
\n" ); document.write( "n=51.76/6 or 8.6 years
\n" ); document.write( "between the 8th and 9th years.\r
\n" ); document.write( "\n" ); document.write( "2000
\n" ); document.write( "2600
\n" ); document.write( "3200
\n" ); document.write( "3800
\n" ); document.write( "4400
\n" ); document.write( "sum for 5 years is 16000
\n" ); document.write( "then
\n" ); document.write( "5000 (21000)
\n" ); document.write( "5600 (26600)
\n" ); document.write( "6200 (32800)
\n" ); document.write( "6800 (39600) on year 9\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
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