21/10

17/4

a) 6/1x 2/5-3/10

= 12/5- 3/10

= 21/10

b) (4/6+5):4/3

= 17/3x 3/4

= 17/4

a) 6 : 5/2 - 3/10 = 12/5 - 3/10 = 21/10

b) 4/6 : 4/3 + 5 : 4/3 = 1/2 + 5 : 4/3 = 1/2 + 15 /4 = 17/4

a)

`6:5/2-3/10`

`=6xx2/5-3/10`

`=12/5-3/10`

`=24/10-3/10`

`=21/10`

b)

`4/6:4/3+5:4/3`

`=2/3xx3/4+5xx3/4`

`=3/4xx(2/3+5)`

`=3/4xx(2/3+15/3)`

`=3/4xx17/3`

`=17/4`

\(a,6:\dfrac{5}{2}-\dfrac{3}{10}\\ =\dfrac{6}{1}:\dfrac{5}{2}-\dfrac{3}{10}\\ =\dfrac{6}{1}\times\dfrac{5}{2}-\dfrac{3}{10}\\ =\dfrac{12}{5}-\dfrac{3}{10}\\ =\dfrac{12\times2}{5\times2}-\dfrac{3}{10}\\ =\dfrac{24}{10}-\dfrac{3}{10}\\ =\dfrac{21}{10}\) 

\(b,\dfrac{4}{6}:\dfrac{4}{3}+5:\dfrac{4}{3}\\ =\dfrac{4}{6}:\dfrac{4}{3}+\dfrac{5}{1}:\dfrac{4}{3}\\ =\dfrac{4}{3}:\left(\dfrac{4}{6}+\dfrac{5}{1}\right)\\ =\dfrac{4}{3}:\left(\dfrac{4}{6}+\dfrac{5\times6}{1\times6}\right)\\ =\dfrac{4}{3}:\left(\dfrac{4}{6}+\dfrac{30}{6}\right)\\ =\dfrac{4}{3}:\dfrac{34}{6}\\ =\dfrac{4}{3}:\dfrac{17}{3}\\ =\dfrac{4}{3}\times\dfrac{3}{17}\\=\dfrac{12}{51} \\ =\dfrac{4}{17}.\)

\(a,6:\dfrac{5}{2}-\dfrac{3}{10}=6\times\dfrac{5}{2}-\dfrac{3}{10}=\dfrac{12}{5}-\dfrac{3}{10}=\dfrac{24}{10}-\dfrac{3}{10}=\dfrac{21}{10}\)

\(b,\dfrac{4}{6}:\dfrac{4}{3}+5:\dfrac{4}{3}=\dfrac{4}{6}\times\dfrac{3}{4}+5\times\dfrac{3}{4}=\dfrac{2}{4}+\dfrac{15}{4}=\dfrac{17}{4}\)

\(a,6:\dfrac{5}{2}-\dfrac{3}{10}=6\times\dfrac{2}{5}-\dfrac{3}{10}=\dfrac{12}{5}-\dfrac{3}{10}=\dfrac{120}{50}-\dfrac{15}{50}=\dfrac{105}{50}=\dfrac{21}{10}\)

\(b,\dfrac{4}{6}:\dfrac{4}{3}+5:\dfrac{4}{3}=\left(\dfrac{4}{6}+5\right):\dfrac{4}{3}=\left(\dfrac{4}{6}+\dfrac{30}{6}\right):\dfrac{4}{3}=\dfrac{34}{6}\times\dfrac{3}{4}=\dfrac{102}{24}=\dfrac{17}{4}\)

éc ô ét giúp mình vớiiiiiii! HUHU=((

a: \(2\dfrac{3}{5}+1\dfrac{2}{5}\cdot\dfrac{31}{2}\)

\(=\dfrac{13}{5}+\dfrac{7}{5}\cdot\dfrac{31}{2}\)

\(=\dfrac{26}{10}+\dfrac{217}{10}=\dfrac{243}{10}\)

b: \(4\dfrac{3}{4}-3\dfrac{2}{3}:1\dfrac{1}{6}\)

\(=\dfrac{19}{4}-\dfrac{11}{3}:\dfrac{7}{6}\)

\(=\dfrac{19}{4}-\dfrac{11}{3}\cdot\dfrac{6}{7}\)

\(=\dfrac{19}{4}-\dfrac{22}{7}\)

\(=\dfrac{19\cdot7-22\cdot4}{28}=\dfrac{45}{28}\)

=(1-2-3+4)+(5-6-7+8)+...+(2017-2018-2019+2020)+2021-2022-2023

=0+0+...+0-1-2023

=-2024

Bằng 2024

 a) 3² . 5³ + 9² = 9 . 125 + 81

= 1 125 + 81 = 1 206

b) 8³ : 4² - 5² = 512 : 16 - 25 = 32 - 25 = 7

c) 3³ . 9² - 5².9 + 18 : 6 = 27 . 81 - 25 . 9 + 3

= 2 187 - 225 + 3 = 1 962 + 3 = 1 965

 a) 3² . 5³ + 9² = 9 . 125 + 81

= 1 125 + 81 = 1 206

b) 8³ : 4² - 5² = 512 : 16 - 25 = 32 - 25 = 7

c) 3³ . 9² - 5².9 + 18 : 6 = 27 . 81 - 25 . 9 + 3

= 2 187 - 225 + 3 = 1 962 + 3 = 1 965

\(a,A=2\sqrt{2}-9\sqrt{2}+16\sqrt{2}-5\sqrt{2}\)

\(=4\sqrt{2}\)

\(b,B=\left|1-\sqrt{5}\right|+\sqrt{5+2\sqrt{5}+1}\)

\(=\left|1-\sqrt{5}\right|+\sqrt{\left(\sqrt{5}+1\right)^2}\)

\(=\left|1-\sqrt{5}\right|+\left|\sqrt{5}+1\right|=\sqrt{5}-1+\sqrt{5}+1=2\sqrt{5}\)

\(c,C=\dfrac{2+\sqrt{6}+2-\sqrt{6}}{\left(2+\sqrt{6}\right)\left(2-\sqrt{6}\right)}=\dfrac{4}{4-6}=-2\)
 

Lời giải:

a. 

\(A=2\sqrt{2}-3\sqrt{18}+4\sqrt{32}-\sqrt{50}=2\sqrt{2}-9\sqrt{2}+16\sqrt{2}-5\sqrt{2}\)

\(=(2-9+16-5)\sqrt{2}=4\sqrt{2}\)

b.

\(B=\sqrt{(1-\sqrt{5})^2}+\sqrt{(\sqrt{5}+1)^2}=|1-\sqrt{5}|+|\sqrt{5}+1|=\sqrt{5}-1+\sqrt{5}+1=2\sqrt{5}\)

c.

\(C=\frac{2+\sqrt{6}+2-\sqrt{6}}{(2-\sqrt{6})(2+\sqrt{6})}=\frac{4}{2^2-6}=-2\)

`a)A=2sqrt2-3sqrt{18}+4sqrt{32}-sqrt{50}`

`=2sqrt2-3sqrt{9.2}+4sqrt{16.2}-sqrt{25.2}`

`=2sqrt2-9sqrt2+16sqrt2-5sqrt2`

`=4sqrt2`

`b)B=sqrt{(1-sqrt5)^2}+sqrt{6+2sqrt5}`

`=sqrt5-1+sqrt{(sqrt5+1)^2}`

`=sqrt5-1+sqrt5+1=2sqrt5`

`c)1/(2-sqrt6)+1/(2+sqrt6)`

`=(2+sqrt6)/(4-6)+(sqrt6-2)/(6-4)`

`=(sqrt6-2-sqrt6-2)/2=-2`

a) \(\dfrac{5}{3}+\dfrac{4}{9}:\dfrac{1}{2}=\dfrac{5}{3}+\dfrac{4}{9}\times2=\dfrac{5}{3}+\dfrac{8}{9}=\dfrac{23}{9}\)

b) \(\dfrac{11}{10}-\dfrac{2}{5}:\dfrac{2}{3}=\dfrac{11}{10}-\dfrac{2}{5}\times\dfrac{3}{2}=\dfrac{11}{10}-\dfrac{3}{5}=\dfrac{11}{10}-\dfrac{6}{10}=\dfrac{5}{10}=\dfrac{1}{2}\)

Câu 4 

\(\dfrac{12\times15\times20}{10\times16\times25}=\dfrac{3\times4\times3\times5\times4\times5}{5\times2\times4\times4\times5\times5}=\dfrac{3\times3}{5\times2}=\dfrac{9}{10}\)

Câu 3:

\(a.\dfrac{5}{3}+\dfrac{4}{9}:\dfrac{1}{2}=\dfrac{5}{3}+\dfrac{8}{9}=\dfrac{15}{9}+\dfrac{8}{9}=\dfrac{23}{9}\)

\(b.\dfrac{11}{10}-\dfrac{2}{5}:\dfrac{2}{3}=\dfrac{11}{10}-\dfrac{3}{5}=\dfrac{11}{10}-\dfrac{6}{10}=\dfrac{5}{10}=\dfrac{1}{2}\)

Câu 4:

\(\dfrac{12\times15\times20}{10\times16\times25}=\dfrac{3\times3\times1}{2\times1\times5}=\dfrac{9}{10}\)

a) Ta có: \(\left(7\sqrt{48}+3\sqrt{27}-2\sqrt{12}\right)\cdot\sqrt{3}\)

\(=\left(7\cdot4\sqrt{3}+3\cdot3\sqrt{3}-2\cdot2\sqrt{3}\right)\cdot\sqrt{3}\)

\(=33\sqrt{3}\cdot\sqrt{3}\)

=99

b) Ta có: \(\left(12\sqrt{50}-8\sqrt{200}+7\sqrt{450}\right):\sqrt{10}\)

\(=\left(12\cdot5\sqrt{2}-8\cdot10\sqrt{2}+7\cdot15\sqrt{2}\right):\sqrt{10}\)

\(=\dfrac{85\sqrt{2}}{\sqrt{10}}=\dfrac{85}{\sqrt{5}}=17\sqrt{5}\)

c) Ta có: \(\left(2\sqrt{6}-4\sqrt{3}+5\sqrt{2}-\dfrac{1}{4}\sqrt{8}\right)\cdot3\sqrt{6}\)

\(=\left(2\sqrt{6}-4\sqrt{3}+5\sqrt{2}-\dfrac{1}{4}\cdot2\sqrt{2}\right)\cdot3\sqrt{6}\)

\(=\left(2\sqrt{6}-4\sqrt{3}+3\sqrt{2}\right)\cdot3\sqrt{6}\)

\(=36-36\sqrt{2}+18\sqrt{3}\)

d) Ta có: \(3\sqrt{15\sqrt{50}}+5\sqrt{24\sqrt{8}}-4\sqrt{12\sqrt{32}}\)

\(=3\cdot\sqrt{75\sqrt{2}}+5\cdot\sqrt{48\sqrt{2}}-4\sqrt{48\sqrt{2}}\)

\(=3\cdot5\sqrt{2}\cdot\sqrt{\sqrt{2}}+4\sqrt{3}\sqrt{\sqrt{2}}\)

\(=15\sqrt{\sqrt{8}}+4\sqrt{\sqrt{18}}\)

a,=\(\left(28\sqrt{3}+9\sqrt{3}-4\sqrt{3}\right).\sqrt{3}\)

   \(=28.3+9.3-4.3=99\)

b,\(=\left(60\sqrt{2}-80\sqrt{2}+175\sqrt{2}\right):\sqrt{10}\)

  \(=155\sqrt{2}:\sqrt{10}=\dfrac{155}{\sqrt{5}}\)

d,Ta có:\(3\sqrt{15\sqrt{50}}+5\sqrt{24\sqrt{8}}-4\sqrt{12\sqrt{32}}\)

        \(=3\sqrt{75\sqrt{2}}+5\sqrt{48\sqrt{2}}-4\sqrt{48\sqrt{2}}\)

        \(=15\sqrt{3\sqrt{2}}+20\sqrt{3\sqrt{2}}-16\sqrt{3\sqrt{2}}\)

        \(=19\sqrt{3\sqrt{2}}\)