Question 371887
Use the FOIL Method,
{{{(3*sqrt(2)-9*sqrt(7))(5*sqrt(2)+15*sqrt(7))=15*sqrt(4)+45sqrt(14)-45*sqrt(14)-135sqrt(49)}}}
{{{(3*sqrt(2)-9*sqrt(7))(5*sqrt(2)+15*sqrt(7))=15*2-135*7}}}
{{{(3*sqrt(2)-9*sqrt(7))(5*sqrt(2)+15*sqrt(7))=30-945}}}
{{{(3*sqrt(2)-9*sqrt(7))(5*sqrt(2)+15*sqrt(7))=highlight(-915)}}}