a) \(\left(x-17\right)\left(x+15\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=17\\x=-15\end{matrix}\right.\)

b) \(\left(6-x\right)\left(x-35\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=6\\x=35\end{matrix}\right.\)

a) x =  40.

b) x = 12.            

c)  x = 10.  

d) x = 15.

x - 29 = 0 + 11

x - 29 = 11

x = 11 + 29

x = 40

\(a,\left(x+3\right)\left(5-x\right)=0\\ \Rightarrow\left\{{}\begin{matrix}x+3=0\\5-x=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=-3\\x=5\end{matrix}\right.\)

\(c,x+17⋮x+3\\ x+3+14⋮x+3\\ 14⋮x+3\\ x+3\inƯ\left(14\right)=\left\{\pm14;\pm7\pm2;\pm1\right\}\)

Từ đó bạn tìm những giá trị của x nha!

1.Tính nhanh nếu có thể:
a) 22 + 23 + 89 + 77
= ( 77 + 23 ) + 22 + 89
= 100 + 22 + 89
= 122 + 89
= 211
b) 35 . 15 + 15 . 65
= 15 . ( 35 + 65 )
= 15 . 100
= 1500
c) 7^2 - 36 : 3^2
=  7^2 - 36 : 9
= 7^2 - 4
= 49 - 4
= 45
d) 476 - {5 . [409 - (8 . 3 - 21)2] - 1724}
= 476 - {5 . [409 - (24 - 21)^2] - 1724}
= 476 - {5 . [409 - (3^2)] -  1724}
= 476 - {5 . [409 - 9 ] - 1724}
= 476 - {5. 400 - 1724}
= 476 - {2000 - 1724}
= 476 - 276
= 200

2. Tìm x, biết:

a) x + 37 = 50

x = 50 - 37

x = 13

b) 2x - 3 = 11

2x = 11 + 3

2x = 14

2x = 2 . 7

`a)`

`x-15 = -21`

`<=> x = -21 + 15`

`<=> x = -6`

`b)`

`42 - x = -7`

`<=> x = 42 - (-7)`

`<=> x = 42 + 7`

`<=> x = 49`

`c)`

`12 - (30-x) = -23`

`30-x = 12 - (-23)`

`30-x = 35`

`x = 30-35`

`x = -5`

`d)`

`31 - (17+x)=18`

`<=> 17+x = 31-18`

`<=> 17+x =13`

`<=> x = 13-17`

`<=> x = -4`

a) \(x-15=-21\)

\(\Rightarrow x=-21+15=-6\)

b) \(42-x=-7\)

\(\Rightarrow x=42+7=49\)

c) \(12-\left(30-x\right)=-23\)

\(\Rightarrow30-x=12+23=35\)

\(\Rightarrow x=30+35=65\)

d) \(31-\left(17+x\right)=18\)

\(\Rightarrow17+x=31-18=13\)

\(\Rightarrow x=13-17=-4\)

a) $x-15=-21$

$\Rightarrow x=-21+15=-6$

b) $42-x=-7$

$x=42+7=49$

c) $12-\left(30-x\right)=-23$

$30-x=12+23=35$

$x=30+35=65$

d) $31-\left(17+x\right)=18$

$17+x=31-18=13$

$x=13-17=-4$

a, bổ sung đề 

 \(\dfrac{29-x}{21}+1+\dfrac{27-x}{23}+1+\dfrac{25-x}{25}+1+\dfrac{23-x}{27}+1+\dfrac{21-x}{29}+1=0\)

\(\Leftrightarrow\dfrac{50-x}{21}+\dfrac{50-x}{23}+\dfrac{50-x}{25}+\dfrac{50-x}{27}+\dfrac{50-x}{29}=0\)

\(\Leftrightarrow\left(50-x\right)\left(\dfrac{1}{21}+\dfrac{1}{23}+\dfrac{1}{25}+\dfrac{1}{27}+\dfrac{1}{29}\ne0\right)=0\Leftrightarrow x=50\)

dài quá làm hộ câu 1-5 thoy

1) x=21-13 

    x=8

2)x=-55+41

   x=-14

3)x=-21+15

    x=-6

4)x=3-3

    x=0

5) x= -98-37

   x=-135

15 ) 57 - ( x - 46 ) = - 13

       57 - x + 46 = -13

       103 - x = -13

       x  = 103 + 13

       x  =  116

16 ) -x - 23 = -38 - 42

       - ( x + 23 )=- ( 38 + 42)

            x + 23 = 38 + 42

             x       = 38 + 42 -23

              x      =  57

17 ) x - ( - 7 ) = -4 – 14

      X + 7 = -18

       X = -18-7

        X  = -25

18 ) 18 - x = -8 - ( - 15 )

       18 – x = 7

               X = 18 – 7

                X = 11

19 ) 45 - (  x + 17 ) = - 26

        45 – x - 17  = -26

        28 – x = -26

                X = 28 + 26

                X = 54

20 ) 3. ( x + 5 ) - x - 11 = 24

       3x +15 –x – 11 = 24

       2x + 4 =24

        2x = 24 – 4

        2x = 20

          X = 20 : 2

         X = 10

21 ) 14 - ( x - 7 ) = - 8 - ( - 9 )

       14 – x + 7 = 1

       21 – x = 1

               X = 21 – 1

               X = 20

22 ) 15 - ( x - 2 ) =  - 7 + 8

         15 – x + 2 = 1

            17 – x = 1

                    X = 17 – 1

                    X = 16

6)  x + ( - 71 ) = ( - 55 ) + 85 

      X – 71 = 30

      X = 30 + 71

      X = 101

7 ) x - ( - 45 ) = - 63 + 27

 X +45 = -16

 X = -16 -45

X = - 61

6)  x + ( - 71 ) = ( - 55 ) + 85

X=30+71=101

7 ) x - ( - 45 ) = - 63 + 27

X=-36-45=-81

8) x + 29 = 43 + ( - 23 )

X=20-29=-9

9 ) x + ( - 47 ) = ( - 62 ) – 17

X=-79+47=-32

10 ) x + 21 = ( - 43 ) + 43

X=0-21=-21

11 ) 31 + x = 45 – 81

 X=-36-31=-67

12 ) x - 12 = ( - 8 ) + (- 7 )

 X=-15+12=-3

13 ) 23 - x = 24 - ( - 16 )

X=23-40=-17

14 ) - 15 - ( - 21 - 3x ) = - 63 -15+21+3x=-63 21+3x=-63-(-15)

 21+3x=-48

3x=-48-21

3x=-69

X=-69 : 3

X=-23

Lời giải:
a.

$(x-15).27=0$

$x-15=0:27=0$

$x=15+0=15$

b.

$23(42-x)=0$

$42-x=0$

$x=42$

c.

$(9x+2).3=60$

$9x+2=60:3=20$

$9x=18$

$x=2$
d.

$71+(26-3x):5=75$

$(26-3x):5=75-71=4$

$26-3x=4.5=20$

$3x=26-20=6$

$x=6:2=3$