1) a - 3√a = √a (√a -3) = √a
a-9 (√a -3)(√a+3) √a +3
2) 6 -√35 = (6-√35)(6-√35) = (6-√35)² = 36 -12√35 +35 =
6+√35 (6+√35)(6-√35) 6² - (√35)² 36-35
= 71 - 12√35 = 71 - 12√35
1
71 -12√35 = 71 -12√35
3) √121 - 10√6.4*√0.1 = 11 - 10√(6.4*0.1) = 11 -10√0.64 =
= 11 -10*0.8 = 11-8=3
4) 2√5 -√45 + √80 = 2√5 - √(9*5) + √(16*5) =
=2√5 - 3√5 + 4√5 = 3√5