Step-by-step explanation:
you multiply both the top and bottom by the root if it was alone.
let's say if we had (1 - sqrt(2)) in the denominator. here we multiply both the numerator and the denominator by the conjugate.
the conjugate is formed by changing the sign between two terms in a binomial. so in this case the conjugate is
(sqrt(2) -1)
make sure to ask if you need any further guidance :)