document.write( "Question 968173: This is so hard for me to grasp for some reason. Can someone help me, please?
\n" ); document.write( " Convert the following partial sums into sigma notation and evaluate the sums:
\n" ); document.write( "a) 1/(1*2^2) + 1/(2*3^2) + 1/(3*4^2)\r
\n" ); document.write( "\n" ); document.write( "b) 3 + 6 + 9 + 12 + 15\r
\n" ); document.write( "\n" ); document.write( "Thank you in advance for your time and assistance! \n" ); document.write( "

Algebra.Com's Answer #591775 by Edwin McCravy(20060) $\"\"$ $\"About$

You can put this solution on YOUR website!
a) 1/(1*2^2) + 1/(2*3^2) + 1/(3*4^2)
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document.write( "Evaluating is just basic fraction math:\r\n" );
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document.write( "For the summation, I'll try some coloring to see if that helps:\r\n" );
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document.write( "Notice that the 1's on top stay the same.\r\n" );
document.write( "Notice that the 2 exponents on the bottom stay the same in all terms.\r\n" );
document.write( "Notice that the red numbers go 1,2,3\r\n" );
document.write( "Notice that the green numbers go 2,3,4, just 1 more than the red numbers.\r\n" );
document.write( "So if k represents a red number, then the corresponding green number is k+1.\r\n" );
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document.write( "So each term is of the form \r\n" );
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document.write( "And k starts at 1 and goes to 3.  We indicate that\r\n" );
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\n" ); document.write( "b) 3 + 6 + 9 + 12 + 15
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document.write( "The evaluation is simple addition, getting 45.\r\n" );
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document.write( "This one is easier than the first one.\r\n" );
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document.write( "They are the first 5 multiples of 3.  They are\r\n" );
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document.write( "The  is the same on all the terms,\r\n" );
document.write( "The numbers after the  go 1,2,3,4,5\r\n" );
document.write( "So if k represents the numbers on the right of the ,\r\n" );
document.write( "then k starts at 1 and goes up to and including 5:\r\n" );
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document.write( "So each term has the form \r\n" );
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document.write( "The summation is\r\n" );
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document.write( "Edwin

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