a) x = 0

b) x = -1

c) x = -9

d) x = 24

e) x = 2 hoặc x = -4

f) x = 5 hoặc x = -3

Bài 15:

a: 2x+x=45

=>3x=45

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

b: 2x+7x=918

=>\(x\cdot\left(7+2\right)=918\)

=>9x=918

=>\(x=\frac{918}{9}=102\)

c: 2x+3x=60+5

=>5x=65

=>\(x=\frac{65}{5}=13\)

d: \(11x+22x=33\cdot2\)

=>33x=66

=>\(x=\frac{66}{33}=2\)

Bài 14:

a: (12-x)(2-x)=0

=>\(\left[\begin{array}{l}12-x=0\\ 2-x=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=12\\ x=2\end{array}\right.\)

b: (x-33)(11-x)=0

=>\(\left[\begin{array}{l}x-33=0\\ 11-x=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=33\\ x=11\end{array}\right.\)

c: (21-x)(12-x)=0

=>\(\left[\begin{array}{l}21-x=0\\ 12-x=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=21\\ x=12\end{array}\right.\)

d: (50-x)(x-150)=0

=>\(\left[\begin{array}{l}50-x=0\\ x-150=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=50\\ x=150\end{array}\right.\)

Bài 13:

a: (x-2)(x-3)=0

=>\(\left[\begin{array}{l}x-2=0\\ x-3=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=2\\ x=3\end{array}\right.\)

b: (x-3)(x-4)=0

=>\(\left[\begin{array}{l}x-3=0\\ x-4=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=3\\ x=4\end{array}\right.\)

c: (x-7)(6-x)=0

=>\(\left[\begin{array}{l}x-7=0\\ 6-x=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=7\\ x=6\end{array}\right.\)

d: (x-3)(x-13)=0

=>\(\left[\begin{array}{l}x-3=0\\ x-13=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=3\\ x=13\end{array}\right.\)

Câu 1: C

Câu 2: A

Câu 3: C

a, x = 384

b, x = 161

c, x = 8

d, x = 15

X

a) Ta có: 2 x + 1 3 = 3 3  nên 2x + l = 3. Do đó x = l.

b) Ta có:  2 x - 1 3 = 5 3  nên 2x  -  1 = 5. Do đó x = 3.

c) Ta có:  x + 1 4 = 2 x 4 nên x +1 = 2x. Do đó x = 1.

d) Ta có:  2 x - 1 5 = x 5 nên 2x  - l = x. Do đó x = l

X+\(\dfrac{2}{7}\)=\(\dfrac{1}{2}\)

X     = \(\dfrac{1}{2}\)-\(\dfrac{2}{7}\)
X     = \(\dfrac{3}{14}\)
Chọn đáp án A. \(\dfrac{3}{14}\)

A

a) x – 12 = 14

x = 14 +12

x = 26

b) 2x – 13 = 3.17

2x = 51 + 13

2x = 64

x = 64 : 2

x = 32

c) x – 43 = 2.18

x = 36 +43

x = 79

d) (x – 14).39 = 0

x – 14 = 0

x = 14

e) (13 – x).28 = 28

13 – x = 1

13 – x = 1

x = 13 – 1

x = 12

f) 22.(35 – x) = 22

35 – x = 1

x = 35 – 1

x = 34

g) x – 24 : 2 = 18

x – 12 = 18

x = 39

h) 400 + (275 – x) = 570

275 – x = 570 – 400

275 – x = 170

x = 275 – 170

x = 105

a) x = 10

b) x = 80.

c) x = 25

a)  x - 12 = 14 x = 14 + 12 x = 26

b)  2 x - 13 = 3 . 17 2 x = 51 + 13 2 x = 64 x = 64 : 2 x = 32

c)  x - 43 = 2 . 18 x = 36 + 43 x = 79

d)  x - 14 . 39 = 0 x - 14 = 0 x = 14

e)  13 - x . 28 = 28 13 - x = 28 : 28 13 - x = 1 x = 13 - 1 x = 12

f) 22 . 35 - x = 22 35 - x = 1 x = 35 - 1 x = 34

g)  x - 24 : 2 = 18 x - 12 = 18 x = 39

h) 400 + 275 - x = 570 275 - x = 570 - 400 275 - x = 170 x = 275 - 170 x = 105