Answer
$30$
Work Step by Step
$\bf{\text{Solution Outline:}}$
To evaluate the given summation expression, $
\displaystyle\sum_{i=1}^3 (i^3-i)
,$ substitute $
i
$ with the values from $
1
$ to $
3
$ and then simplify the expression.
$\bf{\text{Solution Details:}}$
Substituting $
i
$ with the numbers from $
1
$ to $
3
,$ the given expression evaluates to
\begin{array}{l}\require{cancel}
(1^3-1)+(2^3-2)+(3^3-3)
\\\\=
(1-1)+(8-2)+(27-3)
\\\\=
0+6+24
\\\\=
30
.\end{array}
