4x + 3x = 30 – 20 : 10

7x = 30 - 2

7x = 28

x = 28 : 7

x = 4

a) (x - 3) : 2 = 5 14  :  5 12

(x - 3) : 2 = 5 2

(x - 3) : 2 = 25

(x - 3) = 25.2

x = 50 + 3

x = 53

b) 4x + 3x = 30 – 20 : 10

7x = 30 - 2

7x = 28

x = 28 : 7

x = 4

7x=28

x=4

bạn nào bít giúp mik vr

\(4x+3x=30-20:10\)

\(4x+3x=30-2\)

\(4x+3x=28\)

\(\left(4+3\right)x=28\)

\(7x=28\)

\(x=28:7\)

\(x=4\)

Vậy \(x=4\)

Chúc cậu học tốt !!!

a) x+3=12

x=12-3

x=9

b)(x-3):2=5¹⁴:5¹²

=>(x-3):2=5²

=>(x-3):2=25

=>x-3=25.2

=>x-3=50

=>x=50+3

=>x=53

c)4x+3x=30-20:10

=>x(4+3)=30-2

=>7x=28

=>x=28:7

=>x=4

d)2x-138=2³.3²

=>2x-138=8.9

=>2x-138=72

=>2x=72+138

=>2x=210

=>x=210:2

=>x=105

a) x + 3 = 12

x = 12 - 3

x = 9

b) ( x - 3 ) : 2 = 5¹⁴ : 5¹²

( x - 3 ) : 2 = 5^14-12

( x - 3 ) : 2 = 5²

( x - 3 ) : 2 = 25

x - 3 = 50

x = 53

c) 4x + 3x = 30 - 20 : 10

7x = 28

x = 4

d) 2x - 138 = 2³ x 3²

2x - 138 = 8 x 9

2x - 138 = 72

2x = 210

x = 105

\(35-5\left(x-1\right)=10\\ \Leftrightarrow35-5x+5=10\\ \Rightarrow40-5x=10\)

\(\Rightarrow-5x=10-40\\ \Rightarrow-5x=-30\\ \Rightarrow x=\dfrac{-30}{-5}=6\)

c) 

\(24\left(x-16\right)=12^2\)

\(\Rightarrow24x-384=144\\ \Rightarrow24x=144+384\\ \Rightarrow24x=528\\ \Rightarrow x=\dfrac{528}{24}=22\)

d) 

\(\left(x^2-10\right)\div5=3\\ \Rightarrow\left(x^2-10\right)=3\times5\\ \Rightarrow x^2-10=15\)

\(\Rightarrow x^2=15+10\\ \Rightarrow x^2=25\\ \Rightarrow x^2=5^2\Rightarrow x=5\)

Ơ, bn ơi @Kenny sai sai ở đâu thì phải.

\(x+3=12\\ \Rightarrow x=9\)

Vậy \(x=9\).

\(4x+3x=30-20:10\\ \Rightarrow x\left(4+3\right)=30-2\\ \Rightarrow x.7=28\\ \Rightarrow x=4\)

Vậy \(x=4.\)

cứu tôi đây là tìm x thuộc n

đây là tìm x thuộc N

`4x^2=13`

`<=>x^2=13/4`

`<=>x=[+-\sqrt{13}]/2`

Vậy `S={[+-\sqrt{13}]/2}`

`4x^2 = 13`.

`=> x^2 = 13/4`.

`=> x = (sqrt 13)/(sqrt 4)`

`=> x = (+-sqrt 13)/2`.

Vậy `S = (+-sqrt 13)/2`.

\(4x^2=13\)

\(x^2=52\)

\(x=\sqrt{52}\)

Ta có : 

\(\left|3x+18\right|\ge0\) và \(\left|4x-28\right|\ge0\) \(\Rightarrow\) \(\left|3x+18\right|+\left|4y-28\right|\ge0\)

Mà \(\left|3x+18\right|+\left|4y-28\right|\le0\) ( đề bài cho )

\(\Rightarrow\)\(\left|3x+18\right|+\left|4y-28\right|=0\)

\(\Leftrightarrow\)\(\orbr{\begin{cases}3x+18=0\\4y-28=0\end{cases}\Leftrightarrow\orbr{\begin{cases}3x=-18\\4y=28\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=-6\\y=7\end{cases}}}\)

Vậy \(x=-6\) và \(y=7\)

Ta có \(\left|3x+18\right|+\left|4y-28\right|\le0\)

Mà \(\left|3x+18\right|\ge0\forall x;\left|4y-28\right|\ge0\forall y\)

=> |3x+18|+|4y-28|=0

=> 3x+18=4y-28=0

• 3x+18=0 <=> 3x=-18 <=> x=-6

• 4y-28=0 <=> 4y=28 <=> y=7

Vậy ...

thank you very much