Question 476052
{{{(sqrt(8)+5sqrt(10))(sqrt(8) -5sqrt(10))}}}
Use the difference of two squares formula {{{(a+b)(a-b)=a^2-b^2}}}
{{{(sqrt(8)+5sqrt(10))(sqrt(8) -5sqrt(10))=(sqrt(8))^2-(5sqrt(10))^2=8-25*10=8-250=-242}}}