Rút gọn biểu thức \(\sqrt[3]{\left(4-\sqrt{17}\right)^3}\) ta được
A. \(4+\sqrt{17}\). B. \(4-\sqrt{17}\). C. \(\sqrt{17}-4\). D. \(-4-\sqrt{17}\)
Rút gọn biểu thức.
a) \(\sqrt{13+4\sqrt{10}}+\sqrt{13-4\sqrt{10}}\)
b) \(\sqrt{17-3\sqrt{32}}+\sqrt{17-3\sqrt{32}}\)
a: \(=\sqrt{8+2\cdot2\sqrt{2}\cdot\sqrt{5}+5}+\sqrt{8-2\cdot2\sqrt{2}\cdot\sqrt{5}+5}\)
\(=\sqrt{\left(2\sqrt{2}+\sqrt{5}\right)^2}+\sqrt{\left(2\sqrt{2}-\sqrt{5}\right)^2}\)
\(=2\sqrt{2}+\sqrt{5}+2\sqrt{2}-\sqrt{5}=4\sqrt{2}\)
b: \(=2\cdot\sqrt{17-3\sqrt{32}}\)
\(=2\cdot\sqrt{9-2\cdot3\cdot2\sqrt{2}+8}\)
\(=2\left(3-2\sqrt{2}\right)=6-4\sqrt{2}\)
B 5. Rút gọn các biểu thức sau:
a)\(\sqrt{7+4\sqrt{3}}\) b)\(\sqrt{9-4\sqrt{5}}\)
c)\(\sqrt{14+6\sqrt{5}}\) d)\(\sqrt{17-12\sqrt{2}}\)
a.\(\sqrt{7+4\sqrt{3}}=\sqrt{\left(\sqrt{3}+2\right)^2}=\left|\sqrt{3}+2\right|=\sqrt{3}+2\)
b.\(\sqrt{9-4\sqrt{5}}=\sqrt{\left(\sqrt{5}-2\right)^2}=\left|\sqrt{5}-2\right|=\sqrt{5}-2\)
c.\(\sqrt{14+6\sqrt{5}}=\sqrt{\left(\sqrt{5}+3\right)^2}=\left|\sqrt{5}+3\right|=\sqrt{5}+3\)
d.\(\sqrt{17-12\sqrt{2}}=\sqrt{\left(2\sqrt{2}-3\right)^2}=\left|2\sqrt{2}-3\right|=3-2\sqrt{2}\)
Rút gọn biểu thức:
a. \(\sqrt{9-4\sqrt{5}-\sqrt{5}}\)
b.\(\left(\sqrt{2}-3\right)\sqrt{11+6\sqrt{2}}\)
c.\(\sqrt{17-12\sqrt{2}}+\sqrt{17+12\sqrt{2}}\)
Rút gọn các biểu thức sau :
a) \(\sqrt{\left(4+\sqrt{2}\right)^2}\)
b) \(\sqrt{\left(3-\sqrt{3}\right)^2}\)
c) \(\sqrt{\left(4-\sqrt{17}\right)^2}\)
d) \(2\sqrt{3}+\sqrt{\left(2-\sqrt{3}\right)^2}\)
a)\(\sqrt{\left(4+\sqrt{2}\right)^2}=\left|4+\sqrt{2}\right|=4+\sqrt{2}\)
b)\(\sqrt{\left(3-\sqrt{3}\right)^2}=\left|3-\sqrt{3}\right|=3-\sqrt{3}\)
c)\(\sqrt{\left(4-\sqrt{17}\right)^2}=\left|4-\sqrt{17}\right|=\sqrt{17}-4\)
d)\(2\sqrt{3}+\sqrt{\left(2-\sqrt{3}\right)^2}=2\sqrt{3}+\left|2-\sqrt{3}\right|=2\sqrt{3}+2-\sqrt{3}\)
Rút gọn biểu thức \({\left[ {{{\left( {\frac{1}{3}} \right)}^2}} \right]^{\frac{1}{4}}}.{\left( {\sqrt 3 } \right)^5}\), ta được
A. \(\sqrt 3 \).
B. \(3\sqrt 3 \).
C. \(\frac{1}{{\sqrt 3 }}\).
D. 9.
\({\left[ {{{\left( {\frac{1}{3}} \right)}^2}} \right]^{\frac{1}{4}}}.{\left( {\sqrt 3 } \right)^5} = {\left( {\frac{1}{3}} \right)^{2.\frac{1}{4}}}.{\left( {{3^{\frac{1}{2}}}} \right)^5} = {\left( {{3^{ - 1}}} \right)^{\frac{1}{2}}}{.3^{\frac{1}{2}.5}} = {3^{ - \frac{1}{2}}}{.3^{\frac{5}{2}}} = {3^{ - \frac{1}{2} + \frac{5}{2}}} = {3^2} = 9\)
Chọn D.
Bài 1: rút gọn biểu thức sau
d)\(\sqrt{3}+\sqrt{\left(2-\sqrt{3}\right)^2}\)
a)\(\sqrt{\left(4-\sqrt{17}\right)}^2+\sqrt{17}\)
b)\(\sqrt{\left(5+\sqrt{2}\right)}^2-\sqrt{2}\)
c) \(\sqrt{\left(3-\sqrt{3}\right)}^2+\sqrt{3}\)
a)\(\left|4-\sqrt{17}\right|+\sqrt{17}=\sqrt{17}-4+\sqrt{17}=2\sqrt{17}-4\)
b)\(\left|5+\sqrt{2}\right|-\sqrt{2}=5+\sqrt{2}-\sqrt{2}=5\)
c)\(\left|3-\sqrt{3}\right|+\sqrt{3}=3-\sqrt{3}+\sqrt{3}=3\)
d)\(\sqrt{3}+\left|2-\sqrt{3}\right|=\sqrt{3}+2-\sqrt{3}=2\)
d) \(\sqrt{3}+\sqrt{\left(2-\sqrt{3}\right)^2}\)
\(=\sqrt{3}+2-\sqrt{3}\)
\(=2\)
Rút gọn biểu thức :
a. \(5\sqrt{\left(4+2\sqrt{2}\right)^2}\)
b. \(\sqrt{\left(4-\sqrt{17}\right)^2}\)
c. \(2\sqrt{3}+\sqrt{\left(2-\sqrt{3}\right)^2}\)
a) \(5\sqrt{\left(4+2\sqrt{2}\right)^2}=5\left|4+2\sqrt{2}\right|=5\left(4+2\sqrt{2}\right)\)
\(=20+10\sqrt{2}\)
b) \(\sqrt{\left(4-\sqrt{17}\right)^2}=\left|4-\sqrt{17}\right|=\sqrt{17}-4\)
c) \(2\sqrt{3}+\sqrt{\left(2-\sqrt{3}\right)^2}=2\sqrt{3}+\left|2-\sqrt{3}\right|\)
\(=2\sqrt{3}+2-\sqrt{3}=2+\sqrt{3}\)
MÌNH CẦN LUÔN Ạ
Rút gọn biểu thức:
1(2+\(\sqrt{3}\))(7-4\(\sqrt{3}\))
2)\(\left(\sqrt{5-2\sqrt{6}}+\sqrt{2}\right)\sqrt{3}\)
3)\(\sqrt{4+2\sqrt{3}}-\sqrt{5-2\sqrt{6}}+\sqrt{2}\)
4)\(\sqrt{3+2\sqrt{2}}+\sqrt{6-4\sqrt{2}}\)
5)\(2+\sqrt{17-4\sqrt{9+4\sqrt{5}}}\)
\(1,\left(2+\sqrt{3}\right)\left(7-4\sqrt{3}\right)\\ =14-8\sqrt{3}+7\sqrt{3}-12\\ =2-\sqrt{3}\\ 2,\left(\sqrt{5-2\sqrt{6}}+\sqrt{2}\right)\sqrt{3}\\ =\left(\sqrt{\left(\sqrt{3}-\sqrt{2}\right)^2}+\sqrt{2}\right)\sqrt{3}\\ =\left(\left|\sqrt{3}-\sqrt{2}\right|+\sqrt{2}\right)\sqrt{3}\\ =\left(\sqrt{3}-\sqrt{2}+\sqrt{2}\right)\sqrt{3}\\ =\sqrt{3}.\sqrt{3}\\ =3\\ 3,\sqrt{4+2\sqrt{3}}-\sqrt{5-2\sqrt{6}}+\sqrt{2}\\ =\sqrt{\left(\sqrt{3}+1\right)^2}-\sqrt{\left(\sqrt{3}-\sqrt{2}\right)^2}+\sqrt{2}\\ =\left|\sqrt{3}+1\right|-\left|\sqrt{3}-\sqrt{2}\right|+\sqrt{2}\\ =\sqrt{3}+1-\sqrt{3}-\sqrt{2}+\sqrt{2}\\ =1\\ 4,\sqrt{3+2\sqrt{2}}+\sqrt{6-4\sqrt{2}}\\ =\sqrt{\left(1+\sqrt{2}\right)^2}+\sqrt{\left(\sqrt{4}-\sqrt{2}\right)^2}\\ =\left|1+\sqrt{2}\right|+\left|\sqrt{4}-\sqrt{2}\right|\\ =1+\sqrt{2}+\sqrt{4}-\sqrt{2}\\ =1+\sqrt{4}\\ 5,2+\sqrt{17-4\sqrt{9+4\sqrt{5}}}\\ =2+\sqrt{17-8-4\sqrt{5}}\\ =2+\sqrt{\left(\sqrt{5}-2\right)^2}\\ =2+\left|\sqrt{5}-2\right|\\ =2+\sqrt{5}-2\\ =\sqrt{5}\)
1. Khẳng định nào sau đây là đúng?
a, \(3\sqrt{5}=\sqrt{30}\) ; b, \(-3\sqrt{5}=-\sqrt{30}\) ; c, \(-3\sqrt{5}=-\sqrt{45}\) ; d, \(-3\sqrt{5}=\sqrt{45}\);
2. Khẳng định nào sau đây là sai?
a, \(\sqrt{\left(-3\right)^2}.5=-3\sqrt{5}\) b, \(\sqrt{3^2.5}=3\sqrt{5}\)
c, \(\sqrt{9x^2}=-3x\) với x≤0 c, \(\sqrt{\left(x-3\right)^2}=3-x\) với x≤3
3. Khoanh vào chữ đặt trước câu trả lời đúng:
Giá trị của biểu thức \(\dfrac{1}{\sqrt{3}+\sqrt{2}}\) \(\dfrac{1}{\sqrt{3}-\sqrt{2}}\) bằng:
a, 0 ; b, 4 ; c, 2\(\sqrt{2}\) ; d, \(-2\sqrt{2}\)
4. Khoanh vào chữ đặt trước câu trả lời đúng:
Trục căn thức ở mẫu của \(\dfrac{\sqrt{17}}{4+\sqrt{17}}\) ta được:
a, 4 ; b, \(\dfrac{1}{4}\) ; c, \(\sqrt{17}\left(4-\sqrt{17}\right)\) ; d, \(\sqrt{17}\left(\sqrt{17}-4\right)\)
5. Rút gọn các biểu thức (giả sử các biểu thức đều có nghĩa);
a, \(\sqrt{\dfrac{x}{y^3}+\dfrac{2x}{y^4}}\) ; b, \(\dfrac{x-\sqrt{xy}}{\sqrt{x}-\sqrt{y}}\)
c, \(\left(a-b\right)\sqrt{\dfrac{a^2b^2}{\left(a-b\right)^2}}\) ; c, \(\dfrac{a-\sqrt{3a}+3}{a\sqrt{a}+3\sqrt{3}}\)
Rút gọn biểu thức sau:
A = \(\sqrt{7+4\sqrt{3}}-\sqrt{7-4\sqrt{3}}\)
B = \(\sqrt{11+6\sqrt{2}}-\sqrt{11-6\sqrt{2}}\)
C = \(\sqrt{17+12\sqrt{2}}+\sqrt{17-12\sqrt{2}}\)
D = \(\sqrt{9+4\sqrt{5}}-\sqrt{9-4\sqrt{5}}\)
E = \(\sqrt{6+2\sqrt{5}}-\sqrt{6-2\sqrt{5}}\)
\(A=\sqrt{7+4\sqrt{3}}-\sqrt{7-4\sqrt{3}}\)
\(=\sqrt{\left(2+\sqrt{3}\right)^2}-\sqrt{\left(2-\sqrt{3}\right)^2}\)
\(=|2+\sqrt{3}|-|2-\sqrt{3}|\)
\(=2+\sqrt{3}-2+\sqrt{3}\)
\(=2\sqrt{3}\)
\(B=\sqrt{11+6\sqrt{2}}-\sqrt{11-6\sqrt{2}}\)
\(=\sqrt{\left(3+\sqrt{2}\right)^2}-\sqrt{\left(3-\sqrt{2}\right)^2}\)
\(=|3+\sqrt{2}|-|3-\sqrt{2}|\)
\(=3+\sqrt{2}-3+\sqrt{2}\)
\(=2\sqrt{2}\)
\(C=\sqrt{17+12\sqrt{2}}+\sqrt{17-12\sqrt{2}}\)
\(=\sqrt{\left(3+2\sqrt{2}\right)^2}+\sqrt{\left(3-2\sqrt{2}\right)^2}\)
\(=|3+2\sqrt{2}|+|3-2\sqrt{2}|\)
\(=3+2\sqrt{2}+3-2\sqrt{2}\)
\(=6\)
\(D=\sqrt{9+4\sqrt{5}}-\sqrt{9-4\sqrt{5}}\)
\(=\sqrt{\left(2+\sqrt{5}\right)^2}-\sqrt{\left(2-\sqrt{5}\right)^2}\)
\(=|2+\sqrt{5}|-|2-\sqrt{5}|\)
\(=2+\sqrt{5}-\sqrt{5}+2\)
\(=4\)
\(E=\sqrt{6+2\sqrt{5}}-\sqrt{6-2\sqrt{5}}\)
\(=\sqrt{\left(1+\sqrt{5}\right)^2}-\sqrt{\left(1-\sqrt{5}\right)^2}\)
\(=|1+\sqrt{5}|-|1-\sqrt{5}|\)
\(=1+\sqrt{5}-\sqrt{5}+1\)
\(=2\)
\(A=\sqrt{7+4\sqrt{3}}-\sqrt{7-4\sqrt{3}}\)
\(A=\sqrt{3}+2+2-\sqrt{3}\)
A = 2 + 2
A = 4
\(B=\sqrt{11+6\sqrt{2}}-\sqrt{11-6\sqrt{2}}\)
\(B=\sqrt{2}+3+3-\sqrt{2}\)
B = 3 + 3
B = 6
\(C=\sqrt{17+12\sqrt{2}}+\sqrt{17-12\sqrt{2}}\)
\(C=3+2\sqrt{2}+3-2\sqrt{2}\)
C = 3 + 3
C = 6
\(D=\sqrt{9+4\sqrt{5}}-\sqrt{9-4\sqrt{5}}\)
\(D=\sqrt{5}+2-\sqrt{5}+2\)
D = 2 + 2
D = 4
\(E=\sqrt{6+2\sqrt{5}}-\sqrt{6-2\sqrt{5}}\)
\(E=\sqrt{5}+1-\sqrt{5}+1\)
E = 1 + 1
E = 2