# Math Help - Help with sums of integers please.

1. ## Help with sums of integers please.

Question is:

i) Find the sum of the integers from 29 to 107 inclusive.

ii) Hence find the value of

107
E (4 + 3i)
i = 29

Sorry I don't know how to put in the sigma notation above.

I can follow what to do until it gets to the part in brackets (4 + 3i), I am not sure why it is that value? It doesn't seem to fit in with the rest of the equation when I have calculated it.

2. $\sum\limits_{k = 1}^{107} {\left( {4 + 3k} \right)} = \sum\limits_{k = 1}^{107} {\left( 4 \right)} + 3\sum\limits_{k = 1}^{107} {\left( k \right)} = (107)(4) + 3\frac{{\left( {107} \right)\left( {108} \right)}}
{2}$

3. Thanks for replying but unfortunately that has me more confused, why have you swapped i=29 for k=1?

4. Originally Posted by mrszone
Thanks for replying but unfortunately that has me more confused, why have you swapped i=29 for k=1?
To give you a way to solve general questions.
Here is the general idea: $\sum\limits_{k = 29}^{107} {\left( k \right)} = \sum\limits_{k = 1}^{107} {\left( k \right)} - \sum\limits_{k = 1}^{28} {\left( k \right)}$