Đáp án: + Giải thích các bước giải:
`a) \sqrt{12}+\sqrt{48}-\sqrt{75}+\sqrt{108}-\sqrt{147}`
`=\sqrt{2^2 .3}+\sqrt{4^2 .3}-\sqrt{5^2 .3}+\sqrt{6^2 .3}-\sqrt{7^2 .3}`
`=2\sqrt{3}+4\sqrt{3}-5\sqrt{3}+6\sqrt{3}-7\sqrt{3}`
`=0\sqrt{3}`
`=0`
`b) 6\sqrt{18}-5\sqrt{8}+4\sqrt{32}+3\sqrt{128}`
`=6\sqrt{3^2 .2}-5\sqrt{2^2 .2}+4\sqrt{4^2 .2}+3\sqrt{8^2 .2}`
`=6.3\sqrt{2}-5.2\sqrt{2}+4.4\sqrt{2}+3.8\sqrt{2}`
`=18\sqrt{2}-10\sqrt{2}+16\sqrt{2}+24\sqrt{2}`
`=48\sqrt{2}`
`c) (\sqrt{28}-2\sqrt{14}+\sqrt{7}).\sqrt{7}+7\sqrt{8}`
`=\sqrt{7}(3-2\sqrt{2}).\sqrt{7}+7\sqrt{8}`
`=7(3-2\sqrt{2}) +7\sqrt{2^2 .2}`
`=21-14\sqrt{2}+14\sqrt{2}`
`=21`
`d) (15\sqrt{50}+5\sqrt{200}-3\sqrt{450}):\sqrt{10}`
`=15\sqrt{50}:\sqrt{10}+5\sqrt{200}:\sqrt{10}-3\sqrt{450}:\sqrt{10}`
`=15\sqrt{5}+5\sqrt{20}-3\sqrt{45}`
`=15\sqrt{5}+5\sqrt{2^2 .5}-3\sqrt{3^2 .5}`
`=15\sqrt{5}+10\sqrt{5}-9\sqrt{5}`
`=16\sqrt{5}`
