### Home > PC3 > Chapter 4 > Lesson 4.1.1 > Problem4-16

4-16.

​Write each sum in expanded form and calculate its value.

1. $\displaystyle \sum _ { n = 1 } ^ { 4 } n ^ { 2 }$

$1^2+2^2+3^2+4^2$

1. $\displaystyle \sum _ { j = 2 } ^ { 6 } ( 6 j - j ^ { 2 } )$

$(6(2)-2^2)+(6(3)−3^2)+$
$(6(4)-4^2)+(6(5)−5^2)+$
$(6(6)-6^2)$

1. $\displaystyle \sum _ { i = 3 } ^ { 6 } 3 ^ { i }$

Follow the same process as shown in parts (a) and (b).
Be sure to note the starting and ending indices!