Find the sum of ∑ with the top number being 7, the bottom being k=1 and the formula 2k+1
∑(2k+1) from k=1 to 7
= (2*1 + 1) + (2*2 + 1) + (2*3 + 1) + (2*4 + 1) + (2*5 + 1) + (2*6 + 1) + (2*7 + 1)
= 1 + 3 + 5 + 7 + 9 + 11 + 13
= 49
Therefore, the sum is 49.