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Nguyễn Vũ Chí Linh
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Nguyễn Vũ Chí Linh
26 tháng 11 2017 lúc 19:35

Giúp mình :<

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Trần Bảo Châu
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Ngọc Châu
18 tháng 7 2018 lúc 10:22

a) \(\sqrt{200}+2\sqrt{108}-\sqrt{98}+\frac{1}{3}\sqrt{\frac{81}{3}}-3\sqrt{75}\)

\(=10\sqrt{2}+12\sqrt{3}-7\sqrt{2}+\sqrt{3}-15\sqrt{3}\)

\(=3\sqrt{2}-2\sqrt{3}\)

b)\(\left(21\sqrt{\frac{1}{7}}+\frac{1}{2}\sqrt{112}-\frac{14}{3}\sqrt{\frac{9}{7}}+7\right):3\sqrt{7}\)

\(=\left(3\sqrt{7}+2\sqrt{7}-2\sqrt{7}+7\right):3\sqrt{7}\)

\(=\frac{\sqrt{7}\left(3+\sqrt{7}\right)}{3\sqrt{7}}=\frac{\sqrt{7}+3}{3}\)

c)\(\left(\sqrt{27}-\sqrt{125}+\sqrt{45}+\sqrt{12}\right)\left(\sqrt{75}+\sqrt{20}\right)\)

\(=\left(3\sqrt{3}-5\sqrt{5}+3\sqrt{5}+2\sqrt{3}\right)\left(5\sqrt{3}+2\sqrt{5}\right)\)

\(=\left(5\sqrt{3}-2\sqrt{5}\right)\left(5\sqrt{3}+2\sqrt{5}\right)\)

\(=75-20=55\)

d)\(\left(\frac{3}{\sqrt{6}-3}-\frac{3}{\sqrt{6}+3}\right).\frac{3-\sqrt{3}}{2-2\sqrt{3}}-\frac{\sqrt{28-6\sqrt{3}}}{1}\)

\(=\frac{3\left(\sqrt{6}+3\right)-3\left(\sqrt{6}-3\right)}{-3}.\frac{3-\sqrt{3}}{2-2\sqrt{3}}-\sqrt{\left(3\sqrt{3}-1\right)^2}\)

\(=\frac{-6\left(3-\sqrt{3}\right)}{2-2\sqrt{3}}-\left(3\sqrt{3}-1\right)\left(do3\sqrt{3}>1\right)\)

\(=\frac{6\sqrt{3}-18}{2-2\sqrt{3}}-\frac{8\sqrt{3}-20}{2-2\sqrt{3}}\)

\(=\frac{6\sqrt{3}-18-8\sqrt{3}+20}{2-2\sqrt{3}}=\frac{2-2\sqrt{3}}{2-2\sqrt{3}}=1\)

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Mặc tử han
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Chiharu
29 tháng 9 2019 lúc 11:16

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Chiharu
29 tháng 9 2019 lúc 11:42

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Chiharu
29 tháng 9 2019 lúc 11:17

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hoàng thiên
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Chou Chou
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Phổ Cát Tường
11 tháng 12 2019 lúc 22:00

a) = \(5\sqrt{2}-3\sqrt{6}+3\sqrt{2}+5\sqrt{6}\)

= \(8\sqrt{2}+2\sqrt{6}\)

b) = \(2\sqrt{3}-4\sqrt{2}-5\sqrt{3}-\sqrt{2}\)

= \(-3\sqrt{3}-5\sqrt{2}\)

c) = \(\frac{\left(\sqrt{2}-1\right)\left(2+\sqrt{2}\right)}{\left(2-\sqrt{2}\right)\left(2+\sqrt{2}\right)}\)

=\(\frac{2\sqrt{2}+2-2-\sqrt{2}}{2^2-\sqrt{2^2}}\)

=\(\frac{\sqrt{2}}{4-2}\) = \(\frac{\sqrt{2}}{2}\)

d) = \(2\sqrt{6}-5\sqrt{6}+2\sqrt{2}\)

=\(-3\sqrt{6}+2\sqrt{2}\)

e) = \(8\sqrt{6}+3\sqrt{6}-6\sqrt{6}=5\sqrt{6}\)

f) = \(4\sqrt{3}+9\sqrt{3}-4\sqrt{3}=9\sqrt{3}\)

g) = \(10+5\sqrt{10}-5\sqrt{10}=10\)

h) = \(\frac{\left(3+\sqrt{3}\right)\left(3+\sqrt{3}\right)}{\left(3-\sqrt{3}\right)\left(3+\sqrt{3}\right)}+\frac{\left(3-\sqrt{3}\right)\left(3-\sqrt{3}\right)}{\left(3+\sqrt{3}\right)\left(3-\sqrt{3}\right)}\)

= \(\frac{9+3\sqrt{3}+3\sqrt{3}+3}{3^2-\sqrt{3^2}}+\frac{9-3\sqrt{3}-3\sqrt{3}+3}{3^2-\sqrt{3^2}}\)

= \(\frac{12+6\sqrt{3}}{9-3}+\frac{12-6\sqrt{3}}{9-3}\)

= \(\frac{12+6\sqrt{3}+12-6\sqrt{3}}{6}\)

= \(\frac{24}{6}=4\)

k) = \(\left(2\sqrt{7}-2\sqrt{3}+\sqrt{7}\right).\sqrt{7}+2\sqrt{21}\)

= \(\left(3\sqrt{7}-2\sqrt{3}\right).\sqrt{7}+2\sqrt{21}\)

= \(21-2\sqrt{21}+2\sqrt{21}=21\)

l) = \(\frac{\left(2\sqrt{3}-\sqrt{6}\right)\left(\sqrt{8}+2\right)}{\left(\sqrt{8}-2\right)\left(\sqrt{8}+2\right)}\)

= \(\frac{4\sqrt{6}+4\sqrt{3}-4\sqrt{3}-2\sqrt{6}}{\sqrt{8^2}-2^2}\)

= \(\frac{2\sqrt{6}}{8-4}=\frac{2\sqrt{6}}{4}=\frac{\sqrt{6}}{2}\)

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 Khách vãng lai đã xóa
hoàng thiên
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Lân Trần Quốc
27 tháng 7 2019 lúc 22:59

a,

\(2\sqrt{3x}-\sqrt{48x}+\sqrt{108x}+\sqrt{3x}\\ =3\sqrt{3x}-\sqrt{4^2\cdot3x}+\sqrt{6^2\cdot3x}\\ =3\sqrt{3x}-4\sqrt{3x}+6\sqrt{3x}=5\sqrt{3x}\)

b,

\(2\sqrt{25xy}+\sqrt{5}\cdot\sqrt{45x^3y^3}-3y\sqrt{16x^3y}\\ =2\sqrt{5^2xy}+\sqrt{5\cdot45}\cdot\sqrt{\left(xy\right)^2\cdot xy}-3y\sqrt{\left(4x\right)^2\cdot xy}\\ =2\cdot5\sqrt{xy}+\sqrt{225}\cdot xy\sqrt{xy}-3y\cdot4x\sqrt{xy}\\ =10\sqrt{xy}+15xy\sqrt{xy}-12xy\sqrt{xy}=\sqrt{xy}\left(3xy+10\right)\)

c,

\(\frac{2}{\sqrt{3}-1}+\frac{3}{\sqrt{3}-2}+\frac{12}{3-\sqrt{13}}\\ =\frac{2\left(\sqrt{3}+1\right)}{3-1}+\frac{3\left(\sqrt{3}+2\right)}{3-4}+\frac{12\left(3+\sqrt{13}\right)}{9-13}\\ =\frac{2\left(\sqrt{3}+1\right)}{2}+\frac{3\left(\sqrt{3}+2\right)}{-1}+\frac{12\left(3+\sqrt{13}\right)}{-4}\\ =\sqrt{3}+1-3\sqrt{3}-6-9-3\sqrt{13}\\ =-14-2\sqrt{3}-3\sqrt{13}\)

d,

\(\frac{1}{\sqrt{3}-\sqrt{2}}-\frac{2}{\sqrt{3}+\sqrt{5}}-\frac{3}{\sqrt{5}-\sqrt{2}}+\frac{4}{\sqrt{7}+\sqrt{3}}\\ =\frac{\sqrt{3}+\sqrt{2}}{3-2}-\frac{2\left(\sqrt{5}-\sqrt{3}\right)}{5-3}-\frac{3\left(\sqrt{5}+\sqrt{2}\right)}{5-2}+\frac{4\left(\sqrt{7}-\sqrt{3}\right)}{7-3}\\ =\sqrt{3}+\sqrt{2}-\sqrt{5}+\sqrt{3}+\sqrt{5}+\sqrt{2}+\sqrt{7}-\sqrt{3}=\sqrt{7}+\sqrt{3}\)

Chúc bạn học tốt nhaok.

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Hồ Quốc Khánh
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Lãnh Hàn
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Huyền Anh
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