Answer
$-7$
Work Step by Step
$\bf{\text{Solution Outline:}}$
To simplify the given expression, $
(\sqrt{2}+3)(\sqrt{2}-3)
,$ use the special product on multiplying the sum and difference of like terms.
$\bf{\text{Solution Details:}}$
Using the product of the sum and difference of like terms which is given by $(a+b)(a-b)=a^2-b^2,$ the expression above is equivalent
\begin{array}{l}\require{cancel}
(\sqrt{2})^2-(3)^2
\\\\=
2-9
\\\\=
-7
.\end{array}
