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whatevs
Need help on thiss
how did you solve it...i have 5 more problems like this..
is there a way to put it into wolfram?
I looked at it then I thought of a number.
http://www.wolframalpha.com/input/?i=Sum%5B-2+n+%2B+4%2C+%7Bn%2C+4%2C+7%7D%5D
can you help me with these kind of problems?
Given the sequence 9, 12, 15, which of the following is equivalent to
You can split the summations, and evaluate each one separately. \[\sum_{4}^{7}-2n+4 = \sum_{4}^{7}-2n + \sum_{4}^{7}4\] \[= -2\sum_{4}^{7}n + 4\sum_{4}^{7} 1\] \[= -2(\sum_{1}^{7}n - \sum_{1}^{3}n ) + 4(4)\] \[= -2[ 7(7+1)/2 - 3(3+1)/2 ] - 16\] \[= -44 + 16\] \[= -28\]