SOLUTION: Direction: use one of the formulas for special series to find the sum of the series. 42 ∑ 1 i=1 1. 42 is on top of the symbol, i=1 is on bottom and 1 on right side.

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Question 550929: Direction: use one of the formulas for special series to find the sum of the series.
42
∑ 1
i=1
1. 42 is on top of the symbol, i=1 is on bottom and 1 on right side.
2. 5 on top, n on right, n=1 on bottom. the answer is 15 but how?
3. 18 on top, i=1 on bottom, i on right.
4. 20 on top, k on right, k=1 on bottom
5. 6 on top, n^2 on right, n=1 on bottom.
6. 10 on top, i^2 on right, i=1 on bottom
7. 12 on top, i^2 on right, i=1 on bottom
8. 35 on top, k^2 on right, k=1 on bottom
again all these problems are shown in this symbol: ∑
thanks for ur help and happy new year!
please show ur work with each of the problems so i could understand it. thank you very much.
Answer by Edwin McCravy(20056)   (Show Source): You can put this solution on YOUR website!
I'll do 4 of them.  You can do the other 4.  They are similar to these.

1. 42 is on top of the symbol, i=1 is on bottom and 1 on right side. 
 = 1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1 = 42

2. 5 on top, n on right, n=1 on bottom. the answer is 15 but how?
 = 1+2+3+4+5 = 15 We didn't need a formula but we can use it:
               =  =  = 15

4. 20 on top, k on right, k=1 on bottom
 = 1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20

We use the formula   =  =  = 210

8. 35 on top, k^2 on right, k=1 on bottom
 = 1²+2²+3²+4²+5²+6²+7²+8²+9²+10²+11²+12²+13²+14²+15²+16²+17²+18²+19²+20²+21²+22²+23²+24²+25²+26²+27²+28²+29²+30²+31²+32²+33²+34²+35²

We use the formula  =  =  =  = 14910.

Edwin
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