The answer is b. 54- sqr root 2
The expression is: [tex](7- \sqrt{2} )(8+ \sqrt{2} )[/tex]
Multiply values with each other:
[tex](7- \sqrt{2} )(8+ \sqrt{2} )=7*8+7* \sqrt{2}- \sqrt{2}*8- \sqrt{2}* \sqrt{2}= \\
=56+(7 \sqrt{2} -8 \sqrt{2})- (\sqrt{2}) ^{2} =56- \sqrt{2} -2=56-2- \sqrt{2}=54- \sqrt{2}[/tex]
[tex]54- \sqrt{2}[/tex] is 54- sqr root 2
