1) a)sqrt 5(sqrt 10 + sqrt 5 - sqrt 40 / 2) = sqrt 5(sqrt 10 + sqrt 5 - sqrt 10)=sqrt 5 * sqrt 5 = 5
b) 5 - 2sqrt 10 + 2 = 7 - 2 sqrt 10
2)a) (6-sqrt a)(6+sqrt a) / (6-sqrt a)=6+ sqrt a
b)sqrt 5(sqrt 5-1)/sqrt 3(sqrt 5 -1)=sqrt5 / sqrt 3
3)a)3sqrt5 b)5sqrt13 - 5sqrt 3 / 10 = sqrt 13- sqrt 3 / 2