Answer
$-3k^2+4k-7$
Work Step by Step
Removing the grouping symbols and then combining like terms, the given expression, $
(2k-1)-(3k^2-2k+6)
$ simplifies to
\begin{array}{l}\require{cancel}
2k-1-3k^2+2k-6
\\\\=
-3k^2+(2k+2k)+(-1-6)
\\\\=
-3k^2+4k-7
.\end{array}