\(\sqrt{8,1}.\sqrt{250}\)

\(=\sqrt{81}.\sqrt{25}\)

\(=9.5\)

\(=45\)

\(\sqrt{2,5}.\sqrt{360}\)

\(=\sqrt{25}.\sqrt{36}\)

\(=5.6\)

\(=30\)

\(\sqrt{\frac{-49}{-121}}=\sqrt{\frac{49}{121}}\)

\(=\frac{\sqrt{49}}{\sqrt{121}}\)

\(=\frac{7}{11}\)

\(\sqrt{\frac{-36}{-169}}=\sqrt{\frac{36}{169}}\)

\(=\frac{\sqrt{36}}{\sqrt{169}}=\frac{6}{13}\)

Hãy tích cho tui đi

vì câu này dễ mặc dù tui ko biết làm 

Yên tâm khi bạn tích cho tui

Tui sẽ ko tích lại bạn đâu

THANKS

\(a,=\sqrt{\dfrac{81}{25}}=\dfrac{9}{5}\\ b,\approx6,39\\ c,=\sqrt{8,1\cdot20\cdot8}=\sqrt{81\cdot16}=\sqrt{81}\cdot\sqrt{16}=9\cdot4=36\\ d,=\sqrt{\left(\sqrt{6}+\sqrt{5}\right)^2}-\sqrt{\left(\sqrt{6}-\sqrt{5}\right)^2}\\ =\sqrt{6}+\sqrt{5}-\sqrt{6}+\sqrt{5}=2\sqrt{5}\)

a) \(\sqrt{3\dfrac{6}{25}}=\sqrt{\dfrac{81}{25}}=\dfrac{9}{5}\)

b) \(\sqrt[3]{216}=6\)

c) \(\sqrt{8,1}.\sqrt{20}.\sqrt{8}=\dfrac{9\sqrt{10}}{10}.2\sqrt{5}.2\sqrt{2}=36\)

d) \(\sqrt{11+2\sqrt{30}}-\sqrt{11-2\sqrt{30}}=\sqrt{\left(\sqrt{6}+\sqrt{5}\right)^2}-\sqrt{\left(\sqrt{6}-\sqrt{5}\right)^2}=\sqrt{6}+\sqrt{5}-\sqrt{6}+\sqrt{5}=2\sqrt{5}\)

 A=\(\frac{\left(1+...+100\right).\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{7}-\frac{1}{9}\right).\left(63.1,2-21.3,6\right)}{1-2+3-4+...+99-100}\)

A=\(\frac{\left(1+...+100\right).\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{7}-\frac{1}{9}\right).0}{1-2+3-4+...+99-100}\)

A= 0

KẾT QUẢ ĐÚNG 100%

THÔNG MINH

63.1,2=75,6

21.3,6=75,6

=>63.1,2-21.3,6=0

nên biểu thức trên bằng 0

a, \(\sqrt{\frac{289}{25}}=\frac{\sqrt{289}}{\sqrt{25}}=\frac{17}{5}\)

b, \(\sqrt{2\frac{14}{25}}=\sqrt{\frac{64}{25}}=\frac{8}{5}\)

c, \(\sqrt{\frac{0,25}{9}}=\frac{\sqrt{0,25}}{\sqrt{9}}=\frac{0,5}{3}=\frac{1}{2}.\frac{1}{3}=\frac{1}{6}\)

d, \(\sqrt{\frac{8,1}{16}}\)đề có sai ko cô ? 

a) căn 289 / 225 = 17/15

b) căn 64/ 25 = 8/5

c) căn 0,25 / 9 = 1/6

d) căn 8,1 / 1,6 = 9/4

289225=289225=1715.

1425=2.25+1425=6425=6425=85.

0,259=0,259=0,53=530=16.

8,11,6=8116=8116=94.

Dễ thấy 6,3 . 12 - 21 . 3,6 = 63 . 1,2 - 63 . 1,2 = 0

Do đó biểu thức trên bằng 0

a) ; b) ;

c) ; d) .

a) \(\sqrt{\dfrac{289}{225}}=\dfrac{\sqrt{289}}{\sqrt{225}}=\dfrac{17}{15}\)

b) \(\sqrt{2\dfrac{14}{25}}=\dfrac{\sqrt{64}}{\sqrt{25}}=\dfrac{8}{5}\)

c) \(\sqrt{\dfrac{0,25}{9}}=\dfrac{\sqrt{0,25}}{\sqrt{9}}=\dfrac{0,5}{3}=\dfrac{1}{6}\)

d) \(\sqrt{\dfrac{8,1}{1,6}}=\dfrac{\sqrt{81}}{\sqrt{16}}=\dfrac{9}{4}\)

a, \(\sqrt{\dfrac{289}{225}}=\sqrt{\dfrac{17^2}{15^2}}=\dfrac{17}{15}\)

b, \(\sqrt{2\dfrac{14}{25}}=\sqrt{\dfrac{64}{25}}=\sqrt{\dfrac{8^2}{5^2}}=\dfrac{8}{5}\)

c, \(\sqrt{\dfrac{0,25}{9}}=\sqrt{\dfrac{0,5^2}{3^2}}=\dfrac{0,5}{3}\)

d, \(\sqrt{\dfrac{8,1}{1,6}}=\sqrt{\dfrac{0,1}{0,1}.\dfrac{81}{16}}=\sqrt{1.\dfrac{81}{16}}=\dfrac{9}{4}\)

Chúc bạn học tốt!!!

a) \(\sqrt{\dfrac{289}{225}}\)

\(=\dfrac{\sqrt{289}}{\sqrt{225}}\)

\(=\dfrac{\sqrt{17^2}}{\sqrt{15^2}}\)

\(=\dfrac{17}{15}\)

b) \(\sqrt{2\dfrac{14}{15}}\)

\(=\sqrt{\dfrac{44}{15}}\)

\(=\dfrac{\sqrt{44}}{\sqrt{15}}\)

\(=\dfrac{2\sqrt{11}}{\sqrt{15}}\)

\(=\dfrac{2\sqrt{165}}{15}\)

c) \(\sqrt{\dfrac{0,25}{9}}\)

\(=\sqrt{\dfrac{1}{\dfrac{4}{9}}}\)

\(=\dfrac{\dfrac{1}{2}}{3}\)

\(=\dfrac{1}{6}\)

d) \(\sqrt{\dfrac{8,1}{1,6}}\)

\(=\sqrt{5,0625}\)

\(=\sqrt{\dfrac{81}{16}}\)

\(=\dfrac{9}{4}\)

Trl 
8,1 : 0,75 = 10,8

ez ~ mak

10,8 nha bạn

Học tốt

kết quả đúng là 10,8

=1875*8,1*5/3+13,5*625

=13,5*(1875+625)

=13,5*2500

=33750

= 33 750