Question 277443
{{{(2 + sqrt(5))(3- sqrt(5))}}}
Just use FOIL or whatever technique you've learned to multiply something like
(a + b)(c - d)<br>
{{{(2 + sqrt(5))(3- sqrt(5)) = 2*3 + 2*(-sqrt(5)) + sqrt(5)*3 + sqrt(5)*(-sqrt(5)) = 6 + (-2sqrt(5)) + 3sqrt(5) + (-5) = 1 + sqrt(5)}}}