√35 ⋅ 45 ⋅ √7 = √((5⋅7)⋅45⋅7) = √(5 ⋅ 45 ⋅ 72) = 7√(5 ⋅ 45) = 7√(5 ⋅ 5 ⋅ 9) = 7 ⋅ 5 ⋅ 3 = 105
2√7 ⋅ 5√3 ⋅ √21 = 2 ⋅ 5 ⋅ √(7 ⋅ 3 ⋅ 21) = 10 √(7 ⋅ 3 ⋅ 3 ⋅ 7) = 10 ⋅ 7 ⋅ 3 = 210
(√15 - √50) / √30 = (√15 - √(25⋅2)) / √30 = (√15 - 5√2) / √30 = (√15 / √30) - (5√2 / √30) = √(15/30) - 5√(2/30) = √(1/2) - 5√(1/15) = 1/√2 - 5/√15 = (√2)/2 - (5√15)/15 = (√2)/2 - (√15)/3
(√50 - √8) ⋅ √2 = (√(25⋅2) - √(4⋅2)) ⋅ √2 = (5√2 - 2√2) ⋅ √2 = 3√2 ⋅ √2 = 3 ⋅ 2 = 6
(√15 - √8)(√15 + √8) = (√15)2 - (√8)2 = 15 - 8 = 7
Ответ: 2) 105; 4) 210; 6) (√2)/2 - (√15)/3; 8) 6; 10) 7