`(2-sqrt5)sqrt{9+4sqrt5}`
`=(2-sqrt5)sqrt{5+2.2.sqrt5+4}`
`=(2-sqrt5)sqrt{(sqrt5+2)^2}`
`=(2-sqrt5)(2+sqrt5)`
`=4-5=-1`
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Bài 3: Liên hệ giữa phép nhân và phép khai phương
Các câu hỏi tương tự
Tính
1) sqrt{18}.sqrt{2}
2) sqrt{15^2-9^2}
3) sqrt{46-6sqrt{5}}-sqrt{46+6sqrt{5}}
4)sqrt{21+6sqrt{6}}-sqrt{21-6sqrt{6}}
5) left(2+sqrt{5}right).sqrt{9-4sqrt{5}}
6)left(3-sqrt{2}right).sqrt{7+4sqrt{3}}
7)left(sqrt{3}+sqrt{5}right).sqrt{7-2sqrt{10}}
8)left(sqrt{6}+sqrt{10}right).sqrt{4-sqrt{15}}
9) sqrt{2}.left(sqrt{8}-sqrt{32}+3sqrt{18}right)
10) sqrt{2}left(sqrt{2}-sqrt{3-sqrt{5}}right)
11) sqrt{3}-sqrt{2}-sqrt{left(sqrt{3}+sqrt{2}right)^2}
12) left(sqrt{2}-sqrt{3+sqrt{5}}right).sqrt...
Đọc tiếp
Tính
1) \(\sqrt{18}.\sqrt{2}\)
2) \(\sqrt{15^2-9^2}\)
3) \(\sqrt{46-6\sqrt{5}}-\sqrt{46+6\sqrt{5}}\)
4)\(\sqrt{21+6\sqrt{6}}-\sqrt{21-6\sqrt{6}}\)
5) \(\left(2+\sqrt{5}\right).\sqrt{9-4\sqrt{5}}\)
6)\(\left(3-\sqrt{2}\right).\sqrt{7+4\sqrt{3}}\)
7)\(\left(\sqrt{3}+\sqrt{5}\right).\sqrt{7-2\sqrt{10}}\)
8)\(\left(\sqrt{6}+\sqrt{10}\right).\sqrt{4-\sqrt{15}}\)
9) \(\sqrt{2}.\left(\sqrt{8}-\sqrt{32}+3\sqrt{18}\right)\)
10) \(\sqrt{2}\left(\sqrt{2}-\sqrt{3-\sqrt{5}}\right)\)
11) \(\sqrt{3}-\sqrt{2}-\sqrt{\left(\sqrt{3}+\sqrt{2}\right)^2}\)
12) \(\left(\sqrt{2}-\sqrt{3+\sqrt{5}}\right).\sqrt{2}+2\sqrt{5}\)
Rút gọn biểu thức:
a. A= (\(\sqrt{5-2\sqrt{6}}+\sqrt{2}\) ) \(\sqrt{3}\)
b. B= \(\sqrt{4+2\sqrt{3}}+\sqrt{5+2\sqrt{6}}+\sqrt{2}\)
c. C= \(2+\sqrt{17-4\sqrt{9+4\sqrt{5}}}\)
a)sqrt{4+2sqrt{3}} - sqrt{5+2sqrt{6}} + sqrt{2}
b)2 + sqrt{17-4sqrt{9+4sqrt{5}}}
c) sqrt{6}+sqrt{4} / 2sqrt{3}+ sqrt{28}
d) 9sqrt{5}+3sqrt{27}/ sqrt{5}+sqrt{3}
Đọc tiếp
a)\(\sqrt{4+2\sqrt{3}}\) - \(\sqrt{5+2\sqrt{6}}\) + \(\sqrt{2}\)
b)2 + \(\sqrt{17-4\sqrt{9+4\sqrt{5}}}\)
c) \(\sqrt{6}\)+\(\sqrt{4}\) / \(2\sqrt{3}\)+ \(\sqrt{28}\)
d) 9\(\sqrt{5}\)+3\(\sqrt{27}\)/ \(\sqrt{5}\)+\(\sqrt{3}\)
tính
1/ \(\sqrt{1,6}.\sqrt{30}.\sqrt{48}\)
2/ \(\frac{\sqrt{2}}{\sqrt{50}}\)
3/ \(\frac{\sqrt{6^5}}{\sqrt{2^3.3^5}}\)
4/ \(\sqrt{1\frac{9}{6}.5\frac{4}{9}.0,01}\)
1. Rút gọn:
sqrt{8-2sqrt{7}}-sqrt{9-2sqrt{14}}
sqrt{5-2sqrt{6}}-sqrt{11-4sqrt{6}}
2. Tính:
a. 2 + sqrt{17-4sqrt{9}+4sqrt{5}}
b. sqrt{5sqrt{3}+5sqrt{48-10sqrt{7}+4sqrt{3}}}
c. sqrt{4+sqrt{10+2sqrt{5}}}+sqrt{4-sqrt{10+2sqrt{5}}}
3. CM:
a. frac{x+y}{2} sqrt{xy} với x, y 0
b. frac{x}{y}+frac{y}{x} 2 với x,y 0
c. a + b + 1 sqrt{ab} + sqrt{a}+sqrt{b} với a,b 0.
Đọc tiếp
1. Rút gọn:
\(\sqrt{8-2\sqrt{7}}-\sqrt{9-2\sqrt{14}}\)
\(\sqrt{5-2\sqrt{6}}-\sqrt{11-4\sqrt{6}}\)
2. Tính:
a. 2 + \(\sqrt{17-4\sqrt{9}+4\sqrt{5}}\)
b. \(\sqrt{5\sqrt{3}+5\sqrt{48-10\sqrt{7}+4\sqrt{3}}}\)
c. \(\sqrt{4+\sqrt{10+2\sqrt{5}}}+\sqrt{4-\sqrt{10+2\sqrt{5}}}\)
3. CM:
a. \(\frac{x+y}{2}\) >= \(\sqrt{xy}\) với x, y >= 0
b. \(\frac{x}{y}+\frac{y}{x}\) >= 2 với x,y >= 0
c. a + b + 1 >= \(\sqrt{ab}\) + \(\sqrt{a}+\sqrt{b}\) với a,b >= 0.
sqrt{6,5+sqrt{ }12}-sqrt{6.5-sqrt{12}+2sqrt{6}}
sqrt{94-42sqrt{5}-sqrt{94+42sqrt{5}}}
sqrt{50}-2sqrt{72}-3sqrt{2}+sqrt{32}
left(2sqrt{5}-sqrt{125}+sqrt{80}right)sqrt{5}
left(5sqrt{2}-3sqrt{32}+sqrt{200}right)sqrt{8}
(sqrt{45}+frac{1}{2}sqrt{20}-4sqrt{5}-sqrt{left(1-15^2right)})^2
sqrt{9-4sqrt{5}-3sqrt{80}}
Giúp mình với ạ ! Mai mình nộp rồi
Đọc tiếp
\(\sqrt{6,5+\sqrt{ }12}-\sqrt{6.5-\sqrt{12}+2\sqrt{6}}\)
\(\sqrt{94-42\sqrt{5}-\sqrt{94+42\sqrt{5}}}\)
\(\sqrt{50}-2\sqrt{72}-3\sqrt{2}+\sqrt{32}\)
\(\left(2\sqrt{5}-\sqrt{125}+\sqrt{80}\right)\sqrt{5}\)
\(\left(5\sqrt{2}-3\sqrt{32}+\sqrt{200}\right)\sqrt{8}\)
(\(\sqrt{45}+\frac{1}{2}\sqrt{20}-4\sqrt{5}-\sqrt{\left(1-15^2\right)}\))\(^2 \)
\(\sqrt{9-4\sqrt{5}-3\sqrt{80}}\)
Giúp mình với ạ ! Mai mình nộp rồi
Rút gọn biểu thức
a. left(2sqrt{5}-sqrt{7}right)left(2sqrt{5}+sqrt{7}right)
b.left(5sqrt{2}+2sqrt{3}right)left(2sqrt{3}-5sqrt{2}right)
c. sqrt{9+4sqrt{5}}
d. sqrt{14-6sqrt{5}}+sqrt{14+6sqrt{5}}
e. sqrt{55-6sqrt{6}}
f. sqrt{21-6sqrt{6}}
Đọc tiếp
Rút gọn biểu thức
a. \(\left(2\sqrt{5}-\sqrt{7}\right)\left(2\sqrt{5}+\sqrt{7}\right)\)
b.\(\left(5\sqrt{2}+2\sqrt{3}\right)\left(2\sqrt{3}-5\sqrt{2}\right)\)
c. \(\sqrt{9+4\sqrt{5}}\)
d. \(\sqrt{14-6\sqrt{5}}+\sqrt{14+6\sqrt{5}}\)
e. \(\sqrt{55-6\sqrt{6}}\)
f. \(\sqrt{21-6\sqrt{6}}\)
a. \(\sqrt{21+6\sqrt{6}}+\sqrt{9+2\sqrt{18}}-2\sqrt{6+3\sqrt{3}}\)
b. \(\sqrt{6+2\sqrt{2\sqrt{3-\sqrt{4+2\sqrt{3}}}}}\)
c. \(\sqrt{4+\sqrt{15}}-\sqrt{7-3\sqrt{5}}\)
d.\(\sqrt{2+\sqrt{3}}-\sqrt{2-\sqrt{3}}\)
e. \(\sqrt{\frac{9}{4}-\sqrt{2}}+\sqrt{2}\)
Rút gọn biểu thức
A. (2-√3)sqrt{7+4sqrt{3}}
B. sqrt{13+4sqrt{10}}:+:sqrt[]{13-4sqrt{10}}
C.(3 - √2) sqrt{11+6sqrt{2}}
D. (√5+√7) sqrt{12-2sqrt{35}}
E. (√2-√9)sqrt{11+2sqrt{18}}
F. sqrt{46-6sqrt{5}}:+:sqrt{29-12sqrt{5}}
G.sqrt{49-5sqrt{96}}:+:sqrt{49+5sqrt{96}}
H.sqrt{13-sqrt{160::::}}:+:sqrt{53+4sqrt{90}}
Đọc tiếp
Rút gọn biểu thức
A. (2-√3)\(\sqrt{7+4\sqrt{3}}\)
B. \(\sqrt{13+4\sqrt{10}}\:+\:\sqrt[]{13-4\sqrt{10}}\)
C.(3 - √2) \(\sqrt{11+6\sqrt{2}}\)
D. (√5+√7) \(\sqrt{12-2\sqrt{35}}\)
E. (√2-√9)\(\sqrt{11+2\sqrt{18}}\)
F. \(\sqrt{46-6\sqrt{5}}\:+\:\sqrt{29-12\sqrt{5}}\)
G.\(\sqrt{49-5\sqrt{96}}\:+\:\sqrt{49+5\sqrt{96}}\)
H.\(\sqrt{13-\sqrt{160\:\:\:\:}}\:+\:\sqrt{53+4\sqrt{90}}\)