1. ## Sum of...

Write out explicitly what is meant by $\sum_{k=1}^{4}(2k+1)^2$

2. Originally Posted by derek445
Write out explicitly what is meant by $\sum_{k=1}^{4}(2k+1)^2$

$\sum_{k=1}^{4}(2k+1)^2$ means $(2(1)+1)^2 + (2(2)+1)^2+(2(3)+1)^2+(2(4)+1)^2$ ,i.e, the sum of this series with index k starting from 1 to 4