1. 2√8m + √18m − √50m

Упростим корни: \(\sqrt{8m}=2\sqrt{2m}\), \(\sqrt{18m}=3\sqrt{2m}\), \(\sqrt{50m}=5\sqrt{2m}\).

Тогда \(2\cdot2\sqrt{2m}+3\sqrt{2m}-5\sqrt{2m}=2\sqrt{2m}\).

Ответ: \(2\sqrt{2m}\)