Чтобы найти значение выражения √7 ⋅ √28, воспользуемся свойством корней: $$√a ⋅ √b = √(a ⋅ b)$$.
Тогда:
√7 ⋅ √28 = √(7 ⋅ 28) = √(7 ⋅ 7 ⋅ 4) = √(49 ⋅ 4) = √49 ⋅ √4 = 7 ⋅ 2 = 14
Ответ: 14