`a)\sqrt{x}(\sqrt{x}+2)+2\sqrt{x}(\sqrt{x}-2)-(3x-4)`
`=x+2\sqrt{x}+2x-4\sqrt{x}-3x+4`
`=-2\sqrt{x}+4`
`b)3\sqrt{x}(\sqrt{x}+1)-\sqrt{x}(3\sqrt{x}-1)-(4\sqrt{x}-3)`
`=3x+3\sqrt{x}-3x+\sqrt{x}-4\sqrt{x}+3`
`=3`
`c)(\sqrt{x}+1)(\sqrt{x}+2)-3\sqrt{x}(\sqrt{x}-2)-(8\sqrt{x}-5)`
`=x+3\sqrt{x}+2-3x+6\sqrt{x}-8\sqrt{x}+5`
`=-2x+\sqrt{x}+7`