№3

5√1/5 = √1

2√7 = √28

9√2 = √162;

№4

a) 3-b² / √3+b = (√3-b)(√3+b)/√3+b = √3-b

b) 5-√5 / √2-√10 = √5(√5-1) / √2(1-√5) = - √5 / √2

#5

(4√5+3√3)*√5+√60 = 20 + 3√15 + 2√15 = 20+5√15