a) \(\frac{1}{2}x+\frac{3}{5}\left(x-2\right)=3\)

 0,5 x + 0,6 ( x - 2 ) = 3

0,5 x + 0.6 x - 1,2 = 3

1,1 x = 4,2

x = \(\frac{42}{11}\)

Kết luận: 

b) \(\frac{1}{3}x-0,5x=0,75\)

\(\frac{1}{3}x-\frac{1}{2}x=\frac{3}{4}\)

\(-\frac{1}{6}x=\frac{3}{4}\)

\(x=-\frac{9}{2}\)

Kết luận: 

c) \(\frac{3}{-2}x-0,5x=75\%\)

-1,5x - 0,5x = 0,75 

-2x = 0,75 

x = -0,375

Kết luận: 

d) \(-\frac{2}{5}x+\frac{1}{4}=75\%-\frac{3}{4}x\)

-0,4 x + 0,25 = 0,75 - 0,75 x 

-0,4 x + 0,75 x = 0,75 - 0,25

0,35 x = 0,5 

x = \(\frac{10}{7}\)

Kết luận: 

\(a,\frac{1}{2}x+\frac{3}{5}\left(x-2\right)=3\)

\(\frac{1}{2}x+\frac{3}{5}x-\frac{6}{5}=3\)

\(\left(\frac{1}{2}+\frac{3}{5}\right)x-\frac{6}{5}=3\)

\(\frac{11}{10}x-\frac{6}{5}=3\)

\(\frac{11}{10}x=\frac{21}{5}\)

\(x=\frac{42}{11}\)

\(b,\frac{1}{3}x-\frac{1}{2}x=\frac{3}{4}\)

\(\left(\frac{1}{3}-\frac{1}{2}\right)x=\frac{3}{4}\)

\(\frac{-1}{6}x=\frac{3}{4}\)

\(x=\frac{-9}{2}\)

\(c,\frac{3}{-2}x-\frac{1}{2}x=75\%\)

\(\left(\frac{3}{-2}-\frac{1}{2}\right)x=\frac{3}{4}\)

\(-2x=\frac{3}{4}\)

\(x=\frac{-3}{8}\)

\(\frac{-2}{5}x+\frac{1}{4}=75\%-\frac{3}{4}x\)

\(\frac{-2}{5}x+\frac{3}{4}x=\frac{3}{4}-\frac{1}{4}\)

\(\left(\frac{-2}{5}+\frac{3}{4}\right)x=\frac{1}{2}\)

\(\frac{7}{20}x=\frac{1}{2}\)

\(x=\frac{10}{7}\)

a: =25(15+45*3)

=25*150

=3750

b: \(=-10\left(25+75-50\right)=-10\cdot50=-500\)

c: =>3^x-2=27

=>x-2=3

=>x=5

d: =>2x-5=-4

=>2x=1

=>x=1/2

e: =>2(x-1)^2=32

=>(x-1)^2=16

=>x-1=4 hoặc x-1=-4

=>x=-3 hoặc x=5

f:  =>25(x+3)=75

=>x+3=3

=>x=0

ai nhanh nhất mình k cho

Bài 1:

\(A=\frac{1}{\left(1+2\right)}+\frac{1}{\left(1+2+3\right)}+\frac{1}{\left(1+2+3+4\right)}\)\(+\frac{1}{\left(1+2+3+4+5\right)}+...+\)\(\frac{1}{\left(1+2+3+...+10\right)}\)

\(A=\frac{1}{3}+\frac{1}{6}+....+\frac{1}{55}\)

\(A=2\left(\frac{1}{6}+\frac{1}{12}+....+\frac{1}{110}\right)\)

\(A=2\left(\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{10.11}\right)\)

\(A=2\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{10}-\frac{1}{11}\right)\)

\(A=2.\left(\frac{1}{2}-\frac{1}{11}\right)\)

\(A=\frac{9}{11}\)

Bài 2 :

2)  Tử số = 11 x 13 x 15 + 3 x 3 x 3 x 11 x 13 x 15 + 5 x 5 x 5 x 11 x 13 x 15 + 9 x 9 x 9 x 11 x 13 x 15

= (1 + 3 x 3 x 3 + 5 x 5 x 5 + 9 x 9 x9) x 11 x 13 x 15 = (1+27+125+ 729) x 11 x 13 x 15

Mẫu số =  11 x 13 x 17 + 3 x 3 x 3 x 13 x 15 x 19  + 5 x 5 x 5 x 13 x 15 x 17 + 9 x 9 x 9 x 13 x 15 x 17 lớn hơn 11 x 13 x 15 + 3 x 3 x 3 x 13 x 15 x 17 + 5 x 5 x 5 x 13 x 15 x 17 + 9 x 9 x 9 x 13 x 15 x 17  

=  (1 + 3 x 3 x 3 + 5 x 5 x 5 + 9 x 9 x9) 13 x 15 x  17 = (1+27+125+729) x 13 x 15 x 17 

\(\Rightarrow A< \frac{\left(1+27+125+729\right)\times11\times13\times15}{\left(1+27+125+729\right)\times13\times15\times17}\)

\(=\frac{11}{17}\)

\(=\frac{1111}{1717}=B\)

Vậy \(A=B\)

mình đâu biết

\(a,x.\frac{3}{4}-1=\frac{2}{75}\)

\(x.\frac{3}{4}=\frac{77}{75}\)

\(x=\frac{77}{75}:\frac{3}{4}=\frac{308}{225}\)

\(b,3-x:\frac{2}{3}=75\)

\(x:\frac{2}{3}=-72\)

\(x=-72.\frac{2}{3}=-48\)

a) Ta có: \(3\left(x+5\right)-3=2\left(x+1\right)+7\)

\(\Leftrightarrow3x+15-3=2x+2+7\)

\(\Leftrightarrow3x+12=2x+9\)

hay x=-3

b) Ta có: \(15-\left(x+2\right)^2=-1\)

\(\Leftrightarrow\left(x+2\right)^2=16\)

\(\Leftrightarrow\left[{}\begin{matrix}x+2=4\\x+2=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-6\end{matrix}\right.\)

c) Ta có: \(75-\left(2x+1\right)^3=11\)

\(\Leftrightarrow\left(2x+1\right)^3=64\)

\(\Leftrightarrow2x+1=4\)

hay \(x=\dfrac{3}{2}\)

a) Ta có: $3\left(x+5\right)-3=2\left(x+1\right)+7$

$\iff 3x+15-3=2x+2+7$

$\iff 3x+12=2x+9$

hay x=-3

b) Ta có: $15-{}^{}=-1$

$\iff {}^{}=16$

⇔[x+2=4x+2=−4⇔[x=2x=−6⇔[x+2=4x+2=−4⇔[x=2x=−6

c) Ta có: $75-{}^{}$

`3(x+5)-3=2(x+1)+7`

`3x+15-3=2x+2+7`

`x=-3`

.

`15-(x+2)^2=-1`

`(x+2)^2=16`

`(x+2)^2=4^2=(-4)^2`

`[(x+2=4),(x+2=-4):}`

`[(x=2),(x=-6):}`

.

`75-(2x+1)^3=11`

`(2x+1)^3=64`

`(2x+1)^2=4^3`

`2x+1=4`

`x=3/2`

$3(x+5)-3=2(x+1)+7$

$3x+15-3=2x+2+7$

$x=-3$

.

$15-{}^{}=-1$

${}^{}=16$

${}^{}={}^{}={}^{}$

$[\begin{array}{c}x+2=4\\ x+2=-4\end{array}$

$[\begin{array}{c}x=2\\ x=-6\end{array}$

a) Ta có: \(3\left(x+5\right)-3=2\left(x+1\right)+7\)

\(\Leftrightarrow3x-2x=2+7-15+3\)

hay x=-3

b) Ta có: \(15-\left(x+2\right)^2=-1\)

\(\Leftrightarrow\left(x+2\right)^2=16\)

\(\Leftrightarrow\left[{}\begin{matrix}x+2=4\\x+2=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-6\end{matrix}\right.\)

a: \(12:\dfrac{3}{4}+75\%\cdot\dfrac{1}{2}-16\cdot50\%\)

\(=12\cdot\dfrac{4}{3}+\dfrac{3}{4}\cdot\dfrac{1}{2}-16\cdot0,5\)

\(=16-8+\dfrac{3}{8}\)

\(=8,375\)

b: \(75\%\cdot4+22,5:3-1\dfrac{3}{5}\)

\(=0,75\cdot4+7,5-1,6\)

\(=3+7,5-1,6\)

=10,5-1,6

=8,9

1)\(A=\frac{1}{3}+\frac{1}{6}+...+\frac{1}{55}=2\left(\frac{1}{6}+\frac{1}{12}+...+\frac{1}{110}\right)=2\left(\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{10.11}\right)=2\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{10}-\frac{1}{11}\right)=2.\left(\frac{1}{2}-\frac{1}{11}\right)=\frac{9}{11}\)

2) Tử số = 11 x 13 x 15 + 3 x 3 x 3 x 11 x 13 x 15 + 5 x 5 x 5 x 11 x 13 x 15 + 9 x 9 x 9 x 11 x 13 x 15

= (1 + 3 x 3 x 3 + 5 x 5 x 5 + 9 x 9 x9) x 11 x 13 x 15 = (1+27+125+ 729) x 11 x 13 x 15

Mẫu số =  11 x 13 x 17 + 3 x 3 x 3 x 13 x 15 x 19  + 5 x 5 x 5 x 13 x 15 x 17 + 9 x 9 x 9 x 13 x 15 x 17 

lớn hơn 11 x 13 x 15 + 3 x 3 x 3 x 13 x 15 x 17 + 5 x 5 x 5 x 13 x 15 x 17 + 9 x 9 x 9 x 13 x 15 x 17 

=  (1 + 3 x 3 x 3 + 5 x 5 x 5 + 9 x 9 x9) 13 x 15 x  17 = (1+27+125+729) x 13 x 15 x 17

=> \(A

giải giùm mình bài này vớC= (67/111+2/33-15/117)x(1/3-1/4-1/12)

a, 7\(x\) - \(x\) = 5²¹ : 5¹⁹ + 3.2².7

     6\(x\)    = 5³ + 3.4.7

    6\(x\)    = 125 + 12.7

    6\(x\)  = 125 + 84

    6\(x\) = 209

     \(x\)  = 209 : 6

    \(x\) = \(\dfrac{209}{6}\)

b; 11\(x\) - 7\(x\) + 3⁴ : 3³ = 5⁴ + 2\(x\)

    4\(x\) + 3 = 625 + 2\(x\)

   4\(x\) - 2\(x\) = 625 - 3

   2\(x\)        = 622

     \(x\)        = 622 : 2

    \(x\)        = 311

c; 75 - 5.(\(x-3\))³ = 700

          5.(\(x\) - 3)³ = 700 - 75

         5.(\(x\) - 3)³ = - 625

           (\(x\) - 30)³ = - 625 : 5

           (\(x\) - 30)³ = - 125

           (\(x-3\))³ =  (-5)³

           \(x\) - 3 = - 5 

           \(x\)         = - 5 + 3

            \(x\)       = -2

d, 3.(2\(x\) - 1)² = 75

       (2\(x\) - 1)² = 75 : 3

       (2\(x\) - 1)² = 25

       \(\left[{}\begin{matrix}2x-1=-5\\2x-1=5\end{matrix}\right.\)

       \(\left[{}\begin{matrix}2x=-5+1\\2x=5+1\end{matrix}\right.\)

       \(\left[{}\begin{matrix}2x=-4\\2x=6\end{matrix}\right.\)

       \(\left[{}\begin{matrix}x=-2\\x=3\end{matrix}\right.\)

d) \(3.\left(2x-1\right)^2=75\)

\(\left(2x-1\right)^2=75\div3\)

\(\left(2x-1\right)^2=25\)

\(\left(2x-1\right)^2=5^2\) 

\(\Rightarrow2x-1=5\) 

\(2x=5+1\)               

\(2x=6\)                     

\(x=6\div2\)                  

\(x=3\)                        

b) 5( 2x + 3 )( x + 2 ) - 2( 5x - 4 )( x - 1 ) = 75

<=> 5( 2x² + 7x + 6 ) - 2( 5x² - 9x + 4 ) = 75

<=> 10x² + 35x + 30 - 10x² + 18x - 8 = 75

<=> 53x + 22 = 75

<=> 53x = 53

<=> x = 1

c) 2x² + 3( x - 1 )( x + 1 ) = 5x( x + 1 )

<=> 2x² + 3( x² - 1 ) = 5x² + 5x

<=> 2x² + 3x² - 3 - 5x² - 5x = 0

<=> -3 - 5x = 0

<=> -5x = 3

<=> x = -3/5

b, \(5\left(2x+3\right)\left(x+2\right)-2\left(5x-4\right)\left(x-1\right)=75\)

\(\Leftrightarrow10x^2+20x+15x+30-10x^2+10x+8x-8=75\)

\(\Leftrightarrow53x+22=75\Leftrightarrow x=1\)

c, \(2x^2+3\left(x-1\right)\left(x+1\right)=5x\left(x+1\right)\)

\(\Leftrightarrow2x^2+3x^2+3x-3x-3=5x^2+5x\)

\(\Leftrightarrow5x^2-3=5x^2+5x\Leftrightarrow x=-\frac{3}{5}\)