a: =>7x-5x=4+6

=>2x=10

hay x=5

b: =>3x-7x=9+5

=>-4x=14

hay x=-7/2

a). 7x-6 = 5x+4 

=> 7x - 5x = 4 + 6

=> 2x = 10

=> x = 5     

 b) 3x-5 = 7x+9

=> 3x - 7x = 9 + 5

=> -4x = 14

=> x = -7/2

a) x=5

b) x= -7/2

a, -5x -1 = 4

-5x = 5 => x=-1

b, -3x = 13 => -13/3

c, 18x = 15 => x= 5/6

d, 4x=9 => x= 9/4

e, -7x -17 \(\ge\)- 7 => -7x ​\(\ge\)​ 10 => x\(\le\)10/7

f, -11x \(\ge\)16 => x\(\le\)16/11

-3x \(\le\)-1 => x\(\ge\)1/3

bạn có thể làm từng bước ko tắt đc ko ?

20) -5-(x + 3) = 2 - 5x ⇔ -5 - x - 3 = 2 -5x ⇔ 4x = 10 ⇔ x = \(\frac{5}{2}\)

Vậy...

1) 16 - 8x = 0 ⇔ 8(2 - x) = 0⇔ 2 - x = 0 ⇔ x = 2

Vậy phương trình có nghiệm là x = 2

bài lạ thật

ý bạn là như thế này đúng không ạ:

a/ \(x^2-6x+5=0\)

\(x^2-5x-x+5=0\)

\(x\left(x-5\right)-\left(x-5\right)=0\)

\(\left(x-5\right)\left(x-1\right)=0\)

\(\orbr{\begin{cases}x-5=0\rightarrow x=5\\x-1=0\rightarrow x=1\end{cases}}\)

b/\(2x^2+7x+9=0\)

?!

c/ \(4x^2-7x+3=0\)

\(4x^2-4x-3x+3=0\)

\(4x\left(x-1\right)-3\left(x-1\right)=0\)

\(\left(x-1\right)\left(4x-3\right)=0\)

\(\orbr{\begin{cases}x-1=0\Rightarrow x=1\\4x-3=0\Rightarrow x=\frac{3}{4}\end{cases}}\)

d/ \(2\left(x+5\right)=2x+10\)

-,- mik ko rõ đề ạ, sai thì ibox ạ.Cảm ơn

x2−6x+5=0

2x2+7x+9=0

4x2−7x+3=0

2(x+5)=x2+5x

a) 6x - 3 = 8x + 9

    6x      = 8x + 9 + 3

    6x      = 8x + 12

  6x - 6x = 8x - 6x + 12

    0        = 2x + 12

    0 - 12 = 2x

    -12    = 2x

     2x    = -12

       x    = -12 : 2

       x    = -6

b) 7x - 5 = 13 - 5x

    7x      = 13 - 5x + 5

    7x      = 13 + 5 - 5x

    7x      = 18 - 5x

 7x + 5x = 18 - 5x + 5x

   12x     = 18 - (5x - 5x) 

   12x     = 18

   12x     = 18

       x     = 18 : 12

       x     = \(\frac{3}{2}\)(hoặc = 1,5)

c) 2 - 3x = 5x + 10

         3x = 2 - (5x + 10)

         3x = 2 - 5x - 10

         3x = 2 - 10 - 5x

         3x = -8 - 5x

  3x - 3x = -8 - 5x + 3x

         0  = -8 - (5x + 3x)

         0  = -8 - 8x

  -8 - 8x = 0

        8x = -8 - 0

        8x = -8

          x = -8 : 8

          x = -1

\(a,6x-3=8x+9\)

\(-3-9=8x-6x\)

\(-12=2x\)

\(-12:2=x\)

\(-6=x\)

Vậy \(x=-6\)

\(b,7x-5=13-5x\)

\(7x+5x=13+5\)

\(12x=18\)

\(x=\frac{18}{12}=\frac{3}{2}\)

\(c,2-3x=5x+10\)

\(-3x-5x=10-2\)

\(-8x=8\)

\(x=8:-8\)

\(x=-1\)

Học tốt !

a) 6x - 3 = 8x + 9

<=> 6x - 8x = 9 + 3

<=> -2x = 12

<=> x = -6

Vậy S = { -6 }

b) 7x - 5 = 13 - 5x 

<=> 7x + 5x = 13 + 5

<=> 12x = 18

<=> x = 18/12 = 3/2

Vậy S = { 3/2 }

c) 2 - 3x = 5x + 10

<=> -3x - 5x = 10 - 2

<=> -8x = 8

<=> x = -1

Vậy S = { -1 } 

a) x=0

b) x=0

c) x=0

d)x=x

a b c d 

x=x

\(x^2-6x+5=0\)

\(\Leftrightarrow x^2-x-5x+5=0\)

\(\Leftrightarrow x\left(x-1\right)-5\left(x-1\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(x-5\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x-1=0\\x-5=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=1\\x=5\end{cases}}\)

\(2x^2+7x+9=0\)

Đề sai??

\(4x^2-7x+3=0\)

\(\Leftrightarrow4x^2-4x-3x+3=0\)

\(\Leftrightarrow4x\left(x-1\right)-3\left(x-1\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(4x-3\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x-1=0\\4x-3=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=1\\x=\frac{3}{4}\end{cases}}\)

\(2\left(x+5\right)=x^2+5x\)

\(\Leftrightarrow2x+10=x^2+5x\)

\(\Leftrightarrow x^2+5x-2x-10=0\)

\(\Leftrightarrow x^2+3x-10=0\)

\(\Leftrightarrow x^2+5x-2x-10=0\)

\(\Leftrightarrow x\left(x+5\right)-2\left(x+5\right)=0\)

\(\Leftrightarrow\left(x+5\right)\left(x-2\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x+5=0\\x-2=0\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=-5\\x=2\end{cases}}\)

`@` `\text {Ans}`

`\downarrow`

`1.`

\(\left(-4xy\right)\cdot\left(2xy^2-3x^2y\right)\)

`=`\(\left(-4xy\right)\left(2xy^2\right)+\left(-4xy\right)\left(-3x^2y\right)\)

`=`\(-8\left(x\cdot x\right)\left(y\cdot y^2\right)+12\left(x\cdot x^2\right)\left(y\cdot y\right)\)

`=`\(-8x^2y^3+12x^3y^2\)

`2.`

\(\left(-5x\right)\left(3x^3+7x^2-x\right)\)

`=`\(\left(-5x\right)\left(3x^3\right)+\left(-5x\right)\left(7x^2\right)+\left(-5x\right)\left(-x\right)\)

`=`\(-15x^4-35x^3+5x^2\)

`3.`

\(\left(3x-2\right)\left(4x+5\right)-6x\left(2x-1\right)\)

`=`\(3x\left(4x+5\right)-2\left(4x+5\right)-12x^2+6x\)

`=`\(12x^2+15x-8x-10-12x^2+6x\)

`=`\(\left(12x^2-12x^2\right)+\left(15x-8x+6x\right)-10\)

`=`\(13x-10\)

`4.`

\(2x^2\left(x^2-7x+9\right)\)

`=`\(2x^2\cdot x^2+2x^2\cdot\left(-7x\right)+2x^2\cdot9\)

`=`\(2x^4-14x^3+18x^2\)

`5.`

\(\left(3x-5\right)\left(x^2-5x+7\right)\)

`=`\(3x\left(x^2-5x+7\right)-5\left(x^2-5x+7\right)\)

`=`\(3x^3-15x^2+21x-5x^2+25x-35\)

`=`\(3x^3-20x^2+46x-35\)

a, \(\left(3x-7\right)-\left(-5-7x\right)=4x+9\)

\(\Leftrightarrow3x-7+5+7x=4x+9\)

\(\Leftrightarrow3x+7x-4x=9+7-5\)

\(\Leftrightarrow\left(3+7-6\right)x=11\Rightarrow4x=11\Rightarrow x=\frac{11}{4}\notin Z\)

Vậy : \(x\in\varnothing\)

b, \(\left(3x-7\right)-\left(-5-7x\right)=5x+8\)

\(\Leftrightarrow3x-7+5+7x=5x+8\)

\(\Leftrightarrow3x+7x-5x=8+7-5\)

\(\Leftrightarrow\left(3+7-5\right)x=10\Rightarrow5x=10\Rightarrow x=10\div5=2\in Z\)

Vậy : x = 2

c, \(\left(3x-2\right)^3=125\Leftrightarrow\left(3x-2\right)^3=5^3\)

\(\Rightarrow3x-2=5\Rightarrow3x=5+2\Rightarrow3x=7\)

\(\Rightarrow x=7\div3\Rightarrow x=\frac{7}{3}\notin Z\)

Vậy \(x\in\varnothing\)

a, (3x-7)-(-5-7x)=4x+9

3x-7+5+7x=4x+9

3x+7x-4x=9+7-5

6x=11

x=11/6(thuộc Z t/m)

Vậy...

b, (3x-7)-(-5-7x)=5x+8

3x-7+5+7x=5x+8

3x+7x-5x=8+7-5

5x=10

x=2(thuộc Z t/m)

vây...

c, (3x-2)^3=125

(3x-2)^3=5^3

3x-2=5

x=7/3(thuộc Z thỏa mãn)

Vậy...