`(2\sqrt{112} - 5\sqrt{7}+2\sqrt{63}-2\sqrt{28})\sqrt{7}`
`= \sqrt{7}(8\sqrt{7}+6\sqrt{7}-5\sqrt{7}-4\sqrt{7})`
`= 5\sqrt{7}\sqrt{7}`
`= 5 . 7`
`= 35`
`7\sqrt{24} - \sqrt{150} - 5\sqrt{54}`
`= 14\sqrt{6} - 5\sqrt{6} - 15\sqrt{6}`
`= -6\sqrt{6}`
`\sqrt{32} - \sqrt{50} + \sqrt{98} - \sqrt{72}`
`= 4\sqrt{2} - 5\sqrt{2} + 7\sqrt{2} - 6\sqrt{2}`
`= 0`
