Решение
92(1)
2a/(√5a + 5) - 50/(√a + 5) = (2a - 50)/(√a + 50
93(1)
[3/(8 - 3√5) - 3/(8 + 3√5) ] * 19√5 = {[3*(8 + 3√5) - 3*(8 - 3√5)] /[ 8² - (3√5)²] }*19√5 = [(24 + 9√5 - 24 + 9√5)/ 19]*19√5 = 18√5*√5 = 18*5 = 90
90 = 90
доказано
92(3)
[22√a / 11*(√a - √b) ] * [ (√a - √b)*(√a + √b)] / 10√a =
= [2√a*(√a + √b) ] / 10√a = (√a + √b) / 5