\(0,5\sqrt{100}-\sqrt{\frac{4}{25}}=0,5.10-\frac{\sqrt{4}}{\sqrt{25}}=5-\frac{2}{5}=\frac{23}{5}=\frac{138}{30}\)

\(\left(\sqrt{1\frac{1}{9}-\sqrt{\frac{9}{16}}}\right):5=\left(\sqrt{\frac{10}{9}-\frac{3}{4}}\right):5=\sqrt{\frac{13}{36}}:5=\frac{\sqrt{13}}{6}:5=\frac{\sqrt{13}}{30}\)

Vì 13 < 138 nên \(\sqrt{13}< 138\Rightarrow\frac{\sqrt{13}}{30}< \frac{138}{30}\)

Vậy \(0,5\sqrt{100}-\sqrt{\frac{4}{25}}>\left(\sqrt{1\frac{1}{9}-\sqrt{\frac{9}{16}}}\right):5\).

Jdkdk

Jidkri

1.

0,2 . \(\sqrt{100}\) - \(\sqrt{\dfrac{16}{25}}\)

= 0,2 . 10 - \(\dfrac{4}{5}\)

= 2 - \(\dfrac{4}{5}\)

= \(\dfrac{6}{5}\)

1/ \(0,2.\sqrt{100}-\sqrt{\dfrac{16}{25}}\)

\(=0,2.10-0,8\)

\(=2-0,8=1,2\)

2/ \(\dfrac{2^7.9^3}{6^5.8^2}\)

\(=\dfrac{93312}{497664}=\dfrac{3}{16}=0,1875\)

3/ \(\sqrt{0,01}-\sqrt{0,25}\)

\(=0,1-0,5\)

\(=-0,4\)

4/ \(0,5.\sqrt{100}-\sqrt{\dfrac{1}{4}}\)

\(=0,5.10-0,5\)

\(=5-0,5=4,5\)

5/ \(7.\sqrt{0,01}+2.\sqrt{0,25}\)

\(=7.0,1+2.0,5\)

\(=0,7+1=1,7\)

6/ \(0,5.\sqrt{100}-\sqrt{\dfrac{1}{25}}\)

\(=0,5.10-0,2\)

\(=5-0,2=4,8\)

(1+1_1/4+1_1/2+1_3/4+2+2_1/4+2_1/2+2_3/4+......+4_3/4) : 23 tính nhanh !!!!! Ai nhanh mình kêu anh chị mình vào nha !! Mình cần gấp lắm !! Cảm ơn mọi người

1.

a. \(0,5\sqrt{100}-\sqrt{\dfrac{4}{25}}=5-\dfrac{2}{5}=\dfrac{23}{5}>1\)

\(\dfrac{\left(\sqrt{1\dfrac{1}{9}}-\sqrt{\dfrac{9}{16}}\right)}{5}=\dfrac{\dfrac{\sqrt{10}}{3}-\dfrac{3}{4}}{5}=\dfrac{-9+4\sqrt{10}}{60}\approx0,06< 1\)

\(\Rightarrow0,5\sqrt{100}-\sqrt{\dfrac{4}{25}}>\dfrac{\left(\sqrt{1\dfrac{1}{9}}-\sqrt{\dfrac{9}{16}}\right)}{5}\)

2.

Ta có:

\(\left(\sqrt{a+b}\right)^2=a+b\)

\(\left(\sqrt{a}+\sqrt{b}\right)=\left(\sqrt{a}\right)^2+2\sqrt{ab}+\left(\sqrt{b}\right)^2=a+2\sqrt{ab}+b\)

=> \(\sqrt{a+b}< \sqrt{a}+\sqrt{b}\)

1b.

Áp dụng công thức trên

=> \(\sqrt{25+9}< \sqrt{25}+\sqrt{9}\)

2.

\(\sqrt{a+b}< \sqrt{a}+\sqrt{b}\\ \Rightarrow a+b< a+2\sqrt{ab}+b\\ \Rightarrow2\sqrt{ab}>0\\ \Rightarrow\sqrt{ab}>0\)

Luôn đúng với mọi a;b dươn g

=> đpcm

`#3107.101107`

a)

`2/5 \sqrt{25} - 1/2 \sqrt{4}`

`= 2/5 * \sqrt{5^2} - 1/2 * \sqrt{2^2}`

`= 2/5*5 - 1/2*2`

`= 2 - 1`

`= 1`

b)

`0,5*\sqrt{0,09} + 5*\sqrt{0,81}`

`= 0,5*\sqrt{(0,3)^2} + 5*\sqrt{(0,9)^2}`

`= 0,5*0,3 + 5*0,9`

`= 0,15 + 4,5`

`= 4,65`

c)

`2/5\sqrt{25/36} - 5/2\sqrt{4/25}`

`= 2/5*\sqrt{(5^2)/(6^2)} - 5/2*\sqrt{(2^2)/(5^2)}`

`= 2/5*5/6 - 5/2*2/5`

`= 1/3 - 1`

`= -2/3`

d)

`-2 \sqrt{(-36)/(-16)} + 5 \sqrt{(-81)/(-25)}`

`= -2*\sqrt{36/16} + 5*\sqrt{81/25}`

`= -2*\sqrt{(6^2)/(4^2)} + 5*\sqrt{(9^2)/(5^2)}`

`= -2*6/4 + 5*9/5`

`= -3 + 9`

`= 6`

\(100\times\sqrt{0,01}-0,5\times\sqrt{400}+\sqrt{0,09}=100\times0,1-0,5\times20+0,3\)

\(=10-10+0,3=0+0,3=0,3\)

0,3

Dùng mày tính là ra luôn mà

a, = \(\sqrt{2}\)/2 - 1/2 = \(\sqrt{2}-1\)/2

b, = 0,5 . 10 - 1/2 = 5 - 1/2 =9/2

Đáp án là: 

a) = \(\frac{-1+\sqrt{2}}{2}\) .

b) = \(\frac{9}{2}\) .