Answer
$2\sqrt{7}$
Work Step by Step
Substituting the given values of the variables, the expression $\sqrt{b^2-4ac}$ evaluates to
\begin{array}{l}\require{cancel}
\sqrt{(6)^2-4(1)(2)}
\\\\=
\sqrt{36-8}
\\\\=
\sqrt{28}
\\\\=
\sqrt{4\cdot7}
\\\\=
\sqrt{(2)^2\cdot7}
\\\\=
2\sqrt{7}
.\end{array}
