Question 479047
{{{(sqrt(5)+sqrt(6))(sqrt(5)-sqrt(6))}}}
1. You can use FOIL method
First-Outer-Inner-Last
{{{(sqrt(5)+sqrt(6))(sqrt(5)-sqrt(6))=sqrt(5)*sqrt(5)+sqrt(5)*(-sqrt(6))+sqrt(6)*sqrt(5)+sqrt(6)*(-sqrt(6))=(sqrt(5))^2-sqrt(30)+sqrt(30)-(sqrt(6))^2=5-6=-1}}}
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2. But in this case you can use formula {{{(a+b)(a-b)=a^2-b^2}}}
{{{(sqrt(5)+sqrt(6))(sqrt(5)-sqrt(6))=(sqrt(5))^2-(sqrt(6))^2=5-6=-1}}}