4) \(-0{,}5\(\sqrt{40}\)+\(\sqrt{90}\)+\(\sqrt{250}\)=

\(\sqrt{40}=2\sqrt{10}\), \(\sqrt{90}=3\sqrt{10}\), \(\sqrt{250}=5\sqrt{10}\).

\(-0{,}5\cdot2\sqrt{10}+3\sqrt{10}+5\sqrt{10}=(-1+3+5)\sqrt{10}=7\sqrt{10}\).

Ответ: \(7\sqrt{10}\).