Answer
$-18$
Work Step by Step
$\bf{\text{Solution Outline:}}$
To evaluate the given summation expression, $
\displaystyle\sum_{i=2}^5 (6-3i)
,$ substitute $
i
$ with the values from $
2
$ to $
5
$ and then simplify the expression.
$\bf{\text{Solution Details:}}$
Substituting $
i
$ with the numbers from $
2
$ to $
5
,$ the given expression evaluates to
\begin{array}{l}\require{cancel}
(6-3(2))+(6-3(3))+(6-3(4))+(6-3(5))
\\\\=
(6-6)+(6-9)+(6-12)+(6-15)
\\\\=
0-3-6-9
\\\\=
-18
.\end{array}
