\(2x+3=15\\ \Rightarrow2x=15-3=12\\ \Rightarrow x=\dfrac{12}{2}=6\\ ---\\ 28-3x=13\\ \Rightarrow3x=28-13=15\\ \Rightarrow x=\dfrac{15}{3}=5\\ ---\\ \left(x-1954\right).5=50\\ \Rightarrow x-1954=50:5=10\\ \Rightarrow x=10+1954=1964\\ ---\\ x-152:2=46\\ \Rightarrow x-76=46\\ \Rightarrow x=46+76=122\)

a, 2\(x\) + 3 = 15

     2\(x\)       = 12

        \(x\)      = 6

b, 28 - 3\(x\) = 13

           3\(x\) = 28 - 13

           3\(x\)  = 15

             \(x\)   = 5

a) 

\(2x+3=15\)

\(2x=15-3\)

\(2x=12\)

\(x=12:2\)

\(x=6\)

b) \(28-3x=13\)

\(3x=28-13\)

\(3x=15\)

\(x=15:3\)

\(x=5\)

c) \(\left(x-1954\right).5=50\)

\(x-1954=50:5\)

\(x-1954=10\)

\(x=10+1954\)

\(x-1964\)

d) \(x-152:2=46\)

\(x-152=46.2\)

\(x-152=92\)

\(x=92+152\)

\(x=244\)

Câu 15: D

Câu 16: A

Câu 17: B

câu 15: D.40
câu 16: C. 60
câu 17: B.360

\(a)\sqrt{x}=11\\ \Rightarrow\sqrt{x}=\sqrt{11^2}\\ \Rightarrow\sqrt{x}=\sqrt{121}\\ \Rightarrow x=121\\ b)2\sqrt{x}=-\dfrac{13}{15}\\ \Rightarrow\sqrt{x}=-\dfrac{13}{15}:2\\ \Rightarrow\sqrt{x}=-\dfrac{13}{30}\left(ktm\right)\\ c)\sqrt{x}=\sqrt{6}\\ \Rightarrow x=6\)

a: \(\Leftrightarrow\left(2x-5\right)^3=225-4\cdot100=125\)

=>2x-5=5

=>2x=10

hay x=5

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

hay \(x\in\left\{2;5\right\}\)

c: =>x-5-2x-7=-8

=>-x-12=-8

=>x+12=8

hay x=-4

\(\left(2x-5\right)^3=15^2-4.5^2\)

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

\(\Leftrightarrow2x-5=5\)

\(\Leftrightarrow x=5\)

________________________________________________

\(\left(x-2\right)\left(15-3x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-2=0\\15-3x=0\end{matrix}\right.\)

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

____________________________________________

\(\left(x-5\right)-\left(2x+7\right)=-8\)

\(\Leftrightarrow x-5-2x-7=-8\)

\(\Leftrightarrow-x=4\)

\(\Leftrightarrow x=-4\)

a) 17x + 33x = 100

<=> 50x = 100

<=> x = 2

Vậy x = 2

b) 23x + 15 ( x + 7) = 105

<=> 23x + 15x + 105 = 105

<=> 38x = 0

<=> x = 0

Vậy x = 0

c) 32 (x - 11) + 4x = 152

<=> 32x - 352 + 4x = 152

<=> 36x = 504

<=> x = 14

Vậy x = 14

d) 51 ( 3x + 5) - 406 = 22 (3x +50)

<=> 153x + 255 - 406 = 66x + 1100

<=> 87x = 1251

<=> x = \(\frac{1251}{87}\)

Vậy x = \(\frac{1251}{87}\)

Học tốt nhá :))

Bài làm :

\(a,17x+33x=100\)

\(\left(17+33\right)x=100\)

\(50x=100\)

\(x=2\)

\(b,23x+15\left(x+7\right)=105\)

\(23x+15x+105=105\)

\(38x=0\)

\(x=0\)

\(c,32\left(x-11\right)+4x=152\)

\(32x-352+4x=152\)

\(36x=504\)

\(x=14\)

\(d,51\left(3x+5\right)-406=22\left(3x+50\right)\)

\(153x+255-406=66x+1100\)

\(153x-66x=1100+406-255\)

\(87x=1251\)

\(x=\frac{1251}{87}\)

Học tốt

n: (-8)*x+17=-23

=>\(x\cdot\left(-8\right)=-23-17=-40\)

=>\(x\cdot8=40\)

=>\(x=\dfrac{40}{8}=5\)

o: \(\left(-15\right)\cdot x=10\left(-4\right)-5\)

=>\(x\cdot\left(-15\right)=-40-5=-45\)

=>\(x\cdot15=45\)

=>\(x=\dfrac{45}{15}=3\)

p: \(\left(-3\right)\cdot x-4=2\cdot\left(-7\right)+4\)

=>\(\left(-3\right)\cdot x-4=-14+4=-10\)

=>\(x\left(-3\right)=-10+4=-6\)

=>\(3x=6\)

=>\(x=\dfrac{6}{3}=2\)

q: x+x+x+91=-2

=>\(3x+91=-2\)

=>\(3x=-2-91=-93\)

=>\(x=-\dfrac{93}{3}=-31\)

r: \(-152-\left(3x+1\right)=\left(-2\right)\cdot\left(-27\right)\)

=>\(-152-3x-1=54\)

=>\(-153-3x=54\)

=>\(3x=-153-54=-207\)

=>\(x=-\dfrac{207}{3}=-69\)

`a,`

`x*3+7=16`

`=>3x = 16 - 7`

`=> 3x = 9`

`=> x = 9 \div 3`

`=> x = 3`

Vậy, `x = 3`

`b,`

` x- 152 \div 2 = 46?`

`=> x - 76 = 46`

`=> x = 46 + 76`

`=> x = 122`

Vậy, `x = 122.`

`c,`

` 74-2*(x+3)=34`

`=> 2(x + 3) = 74 - 34`

`=> 2(x+2) = 40`

`=> x + 2 = 40 \div 2`

`=> x + 2 = 20`

`=> x = 20 - 2`

`=> x = 18`

Vậy, `x = 18.`

Đáp án cần chọn là: A