Question

Oblicz.
√128 - √72 =
3√108 - 3√32 =
3√80 + 3√125 =

Answer 1

√128 - √72 = √(64 * 2) - √(36 * 2) = 8√2 - 6√2 = 2√2
3√108 - 3√32 = 3√(36 * 3) - 3√(16 * 2) = 3 * 6√3 - 3 * 4√2 = 18√3 - 12√2 = 
= 6(3√3 - 2√2)
3√80 + 3√125 = 3√(16 * 5) + 3√(25 * 5) = 3 * 4√5 + 3 * 5√5 = 12√5 + 15√5 = 27√5