Question 117095
numerator 4
denominator -2+sqrt7


{{{4/(-2+sqrt(7))}}}  multiply numerator and denominator by{{{-2-sqrt(7)}}}--the conjugate of {{{-2+sqrt(7)}}}.  This will get rid of the radical in the denominator.

{{{4(-2-sqrt(7))/(-2+sqrt(7))(-2-sqrt(7))}}} and this equals

{{{4(-2-sqrt(7))/(4-2sqrt(7)+2sqrt(7)-7)}}} which equals
{{{-4(2+sqrt(7))/-3}}} or
{{{(4/3)(2+sqrt(7))}}}


Hope this helps---ptaylor