\(=\dfrac{2\sqrt{5}\left(\sqrt{5}+\sqrt{2}\right)}{\sqrt{5}+\sqrt{2}}-\dfrac{8\left(\sqrt{5}+1\right)}{4}\\ =2\sqrt{5}-2\sqrt{5}-2=-2\)
Đúng 1
Bình luận (0)
Chương I - Căn bậc hai. Căn bậc ba
Các câu hỏi tương tự
Tính giá trị các biểu thức sau
1.dfrac{1}{sqrt{1}-sqrt{2}}-dfrac{1}{sqrt{2}-sqrt{3}}+dfrac{1}{sqrt{3}-sqrt{4}}-dfrac{1}{sqrt{4}-sqrt{5}}+dfrac{1}{sqrt{5}-sqrt{6}}-dfrac{1}{sqrt{6}-sqrt{7}}+dfrac{1}{sqrt{7}-sqrt{8}}-dfrac{1}{sqrt{8}-sqrt{9}}
2.dfrac{1}{2sqrt{1}+1sqrt{2}}+dfrac{1}{3sqrt{2}+2sqrt{3}}+dfrac{1}{4sqrt{3}+3sqrt{4}}+dfrac{1}{5sqrt{4}+4sqrt{5}}+dfrac{1}{6sqrt{5}+5sqrt{6}}+dfrac{1}{7sqrt{6}+6sqrt{7}}
giúp mk vs ạ
Đọc tiếp
Tính giá trị các biểu thức sau
1.\(\dfrac{1}{\sqrt{1}-\sqrt{2}}-\dfrac{1}{\sqrt{2}-\sqrt{3}}+\dfrac{1}{\sqrt{3}-\sqrt{4}}-\dfrac{1}{\sqrt{4}-\sqrt{5}}+\dfrac{1}{\sqrt{5}-\sqrt{6}}-\dfrac{1}{\sqrt{6}-\sqrt{7}}+\dfrac{1}{\sqrt{7}-\sqrt{8}}-\dfrac{1}{\sqrt{8}-\sqrt{9}}\)
2.\(\dfrac{1}{2\sqrt{1}+1\sqrt{2}}+\dfrac{1}{3\sqrt{2}+2\sqrt{3}}+\dfrac{1}{4\sqrt{3}+3\sqrt{4}}+\dfrac{1}{5\sqrt{4}+4\sqrt{5}}+\dfrac{1}{6\sqrt{5}+5\sqrt{6}}+\dfrac{1}{7\sqrt{6}+6\sqrt{7}}\)
giúp mk vs ạ
Câu 1 :Tính : B ( 3 - sqrt{5}) ( sqrt{5} + 3 )Câu 2 : Rút gọn : dfrac{sqrt{5}+1}{3-2sqrt{2}}-dfrac{sqrt{10}}{sqrt{5}-2}+3left(sqrt{2}-sqrt{5}right)Câu 3: left(dfrac{sqrt{x}+sqrt{y}}{1-sqrt{xy}}+dfrac{sqrt{x}+sqrt{y}}{1+sqrt{xy}}right):left(1+dfrac{x+y+2xy}{1-xy}right)a, Rút gọn biểu thức ab, Tính giá trị của A khi x + dfrac{2}{2+sqrt{3}}
Đọc tiếp
Câu 1 :Tính : B = ( 3 - \(\sqrt{5}\)) ( \(\sqrt{5}\) + 3 )
Câu 2 : Rút gọn : \(\dfrac{\sqrt{5}+1}{3-2\sqrt{2}}-\dfrac{\sqrt{10}}{\sqrt{5}-2}+3\left(\sqrt{2}-\sqrt{5}\right)\)
Câu 3: \(\left(\dfrac{\sqrt{x}+\sqrt{y}}{1-\sqrt{xy}}+\dfrac{\sqrt{x}+\sqrt{y}}{1+\sqrt{xy}}\right):\left(1+\dfrac{x+y+2xy}{1-xy}\right)\)
a, Rút gọn biểu thức a
b, Tính giá trị của A khi x + \(\dfrac{2}{2+\sqrt{3}}\)
Tính:a. 5sqrt{2}-2sqrt{48}+6sqrt{75}-sqrt{108}b.2sqrt{147}-dfrac{3}{32}sqrt{192}+dfrac{4}{18}sqrt{243}-dfrac{1}{10}sqrt{300}c. -dfrac{1}{2}sqrt{108}+dfrac{1}{15}sqrt{75}-dfrac{1}{22}sqrt{363}+sqrt{12} d. dfrac{5}{8}sqrt{48}-dfrac{1}{33}sqrt{363}+dfrac{3}{14}sqrt{147}-dfrac{1}{4}sqrt{192}e. dfrac{3}{2}sqrt{12}+dfrac{7}{5}sqrt{75}-dfrac{9}{10}sqrt{300}+dfrac{11}{6}sqrt{108}
Đọc tiếp
Tính:
a. \(5\sqrt{2}-2\sqrt{48}+6\sqrt{75}-\sqrt{108}\)
b.\(2\sqrt{147}-\dfrac{3}{32}\sqrt{192}+\dfrac{4}{18}\sqrt{243}-\dfrac{1}{10}\sqrt{300}\)
c. \(-\dfrac{1}{2}\sqrt{108}+\dfrac{1}{15}\sqrt{75}-\dfrac{1}{22}\sqrt{363}+\sqrt{12}\)
d. \(\dfrac{5}{8}\sqrt{48}-\dfrac{1}{33}\sqrt{363}+\dfrac{3}{14}\sqrt{147}-\dfrac{1}{4}\sqrt{192}\)
e. \(\dfrac{3}{2}\sqrt{12}+\dfrac{7}{5}\sqrt{75}-\dfrac{9}{10}\sqrt{300}+\dfrac{11}{6}\sqrt{108}\)
Tính:
\(A=3\sqrt{20}-\sqrt{45}+2\sqrt{18}+\sqrt{72}\)
\(B=\dfrac{12}{3-\sqrt{5}}-\dfrac{16}{\sqrt{5}+1}\)
\(C=10\sqrt{\dfrac{1}{5}}+\dfrac{1}{5}\sqrt{125}-2\sqrt{20}\)
\(E=\sqrt{\left(\sqrt{3}+1\right)^2}-\sqrt{\left(\sqrt{3}-2\right)^2}\)
\(F=\sqrt{6+2\sqrt{5}}-\sqrt{9-4\sqrt{5}}\)
Tính:
\(A=3\sqrt{20}-\sqrt{45}+2\sqrt{18}+\sqrt{72}\)
\(B=\dfrac{12}{3-\sqrt{5}}-\dfrac{16}{\sqrt{5}+1}\)
\(C=10\sqrt{\dfrac{1}{5}}+\dfrac{1}{5}\sqrt{125}-2\sqrt{20}\)
\(E=\sqrt{\left(\sqrt{3}+1\right)^2}-\sqrt{\left(\sqrt{3}-2\right)^2}\)
\(F=\sqrt{6+2\sqrt{5}}-\sqrt{9-4\sqrt{5}}\)
Rút gọn
a) 2sqrt{5}-sqrt{125}-sqrt{80}+sqrt{605}
b) dfrac{10+2sqrt{10}}{sqrt{5}+sqrt{2}}+dfrac{8}{1-sqrt{5}}
c) sqrt{15-sqrt{216}}+sqrt{33-12sqrt{6}}
d) dfrac{2sqrt{8}-sqrt{12}}{sqrt{18}-sqrt{48}}-dfrac{sqrt{5}+sqrt{27}}{sqrt{30}+sqrt{162}}
e) 2sqrt{dfrac{16}{3}}-3sqrt{dfrac{1}{27}}-6sqrt{dfrac{4}{75}}
Đọc tiếp
Rút gọn
a) \(2\sqrt{5}-\sqrt{125}-\sqrt{80}+\sqrt{605}\)
b) \(\dfrac{10+2\sqrt{10}}{\sqrt{5}+\sqrt{2}}+\dfrac{8}{1-\sqrt{5}}\)
c) \(\sqrt{15-\sqrt{216}}+\sqrt{33-12\sqrt{6}}\)
d) \(\dfrac{2\sqrt{8}-\sqrt{12}}{\sqrt{18}-\sqrt{48}}-\dfrac{\sqrt{5}+\sqrt{27}}{\sqrt{30}+\sqrt{162}}\)
e) \(2\sqrt{\dfrac{16}{3}}-3\sqrt{\dfrac{1}{27}}-6\sqrt{\dfrac{4}{75}}\)
Rút gọn:
a) \(2\sqrt{5}-\sqrt{125}-\sqrt{80}+\sqrt{605}\)
b) \(\dfrac{10+2\sqrt{10}}{\sqrt{5}+\sqrt{2}}+\dfrac{8}{1-\sqrt{5}}\)
Rút gọn biểu thức:
a) dfrac{sqrt{9-2sqrt{6}}-sqrt{6}}{sqrt{3}} b)dfrac{5+sqrt{5}}{5-sqrt{5}}+dfrac{5-sqrt{5}}{5+sqrt{5}}
c) sqrt{13+30sqrt{2+sqrt{9+4sqrt{2}}}} d) sqrt{8+2sqrt{10+2sqrt{5}}}+sqrt{8-2sqrt{10+2sqrt{5}}}
e) dfrac{2sqrt{3+sqrt{5-sqrt{13+sqrt{48}}}}}{sqrt{6}-sqrt{2}} f) sqrt{9-sqrt{5sqrt{3}+5sqrt{8+10sqrt{7-4sqrt{3}}}}}
Đọc tiếp
Rút gọn biểu thức:
a) \(\dfrac{\sqrt{9-2\sqrt{6}}-\sqrt{6}}{\sqrt{3}}\) b)\(\dfrac{5+\sqrt{5}}{5-\sqrt{5}}+\dfrac{5-\sqrt{5}}{5+\sqrt{5}}\)
c) \(\sqrt{13+30\sqrt{2+\sqrt{9+4\sqrt{2}}}}\) d) \(\sqrt{8+2\sqrt{10+2\sqrt{5}}}+\sqrt{8-2\sqrt{10+2\sqrt{5}}}\)
e) \(\dfrac{2\sqrt{3+\sqrt{5-\sqrt{13+\sqrt{48}}}}}{\sqrt{6}-\sqrt{2}}\) f) \(\sqrt{9-\sqrt{5\sqrt{3}+5\sqrt{8+10\sqrt{7-4\sqrt{3}}}}}\)
Rút gọn:
A= \(\dfrac{1}{\sqrt{7-\sqrt{24}}+1}-\dfrac{1}{\sqrt{7+\sqrt{24}}+1}\)
B=\(\dfrac{2}{\sqrt{8-2\sqrt{5}}}-\dfrac{1}{\sqrt{5-2\sqrt{6}}}-\dfrac{3}{\sqrt{7+2\sqrt{10}}}\)