Posted by **Sandra** on Thursday, December 15, 2011 at 8:44pm.

1.Write 4+6+8+10 in sigma notation:

I came up with sigma in the middle

3 on top

j=0 on the bottom

2n+4 to the right of the signma sign

2. Find the 10th term of the sequence

-1/5,-1/20,-1/80 this was a geometric sequence so I said a(subscript10) = -1/5*1/4^(10-1)

=-1/5*(1/4)^9 = -1/5*1/2621444

= -1/1310702

- Pre-Calc-Please check answer -
**Sandra**, Thursday, December 15, 2011 at 8:44pm
Should be sigma sign not signma sign

- Pre-Calc-Please check answer -
**Steve**, Friday, December 16, 2011 at 12:39am
1. either have n=0 under the sigma, or use (2j+4) as the summand.

2. good work, but

4^9 = 262144. you have an extra 4.

1/5 * 1/262144 = 1/1310720

that dyslexia will get you every time. I noticed it right off, because no multiple of 5 ends in 2 :-)

did you hear about the dyslexic devil worshiper? He sold his soul to Santa.

- Pre-Calc-Please check answer -
**Sandra**, Friday, December 16, 2011 at 8:47am
Thank you-I see where I made the mistake

Funny!! I like that!

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