Find the indicated sum:\r
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document.write( "6 + 12 + 18 + ... + 300
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document.write( "One of two formula for the sum of n terms is\r\n" );
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document.write( "We have a1 = 6 and an = 300\r\n" );
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document.write( "so we must find d and n\r\n" );
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document.write( "6 + 12 + 18 + ... + 300\r\n" );
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document.write( "First we determine the common difference, d\r\n" );
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document.write( "d = (2nd term)-(1st term) = (3rd term)-(2nd term) = 12-6 = 18-12 = 6\r\n" );
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document.write( "Next we determine the number of terms, n:\r\n" );
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document.write( "We use the formula for the nth term\r\n" );
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document.write( "Now we can substitute in\r\n" );
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document.write( "Notice that we could have used the other sum formula just as well:\r\n" );
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document.write( "Edwin
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