### Home > APCALC > Chapter 2 > Lesson 2.1.2 > Problem2-22

2-22.

Rewrite the summation notation $\displaystyle\sum _ { i = 6 } ^ { 11 } f ( i )$ so that the index goes from $i = 10$ to $i = 15$ and the result will be the same for any given function.

If we are going to shift the index $4$ units to the right, we also want to shift the argument $4$ units to the right.

$\displaystyle\sum_{i=6}^{11}f(i)=\sum_{i=10}^{15}f(i-4)$