x²+5x=0

x(x+5)=0

*x=0

*x+5=0

      x=0-5

      x=-5

Vậy......................

1) x = 0

2) x = 2

3) không biết (thông cảm)

4) x > 0

5) x < 0

Mn giải hộ mk nha...mk cần gấp

1, x\(^2\) - 5x = 0

\(\Rightarrow\)x(x-5) = 0

Th1: x = 0

Th2: x- 5 =0

x = 5

2, \(|x-9|\) .( -8) = - 16

\(|x-9|\) = (- 16). ( -8) = 128

Th1: x - 9 = 128

x = 128 + 9 = 137

Th2: x - 9 = - 128

x = -128 + 9 = - 119

3, Th1: 4- 5x = 24

5x = 4- 24 = -20

x = - 20 :5 = -4

Th2: 4- 5x = -24

5x = 4- (-24) = 28

x = 28 :5= 5,6

Vì x < hoặc = 0 \(\Rightarrow\) x = -4

4, x.( x - 2) > 0

\(\Rightarrow\) x và ( x- 2) cùng dấu

Th1: x và (x -2) cùng dương

+ \(\Rightarrow\) x > 0

+ (x - 2) > 0 \(\Rightarrow\) x > 2

Th2: x và ( x- 2) cùng âm

+ \(\Rightarrow\) x < 0

+ ( x - 2) < 0 \(\Rightarrow\) x < 2

Từ 2 trường hợp trên \(\Rightarrow\) x > 2 hoặc x <2

5, x.( x - 2) < 0

\(\Rightarrow\) x và ( x- 2) khác dấu

Th1: x âm và ( x- 2) dương

+ \(\Rightarrow\) x < 0

+ (x -2 ) > 0 \(\Rightarrow\) x > 2

Th2: x dương và ( x- 2 ) âm

+ \(\Rightarrow\) x >0

+ (x - 2) < 0 \(\Rightarrow\) x < 2

x²+5.x=0

x.x+5.x=0

x.(x+5)=0

*x=0

*x+5=0

     x=0-5

     x=-5

Vậy x=0 hoặc x=-5

17x + 3. ( -16x – 37) = 2x + 43 - 4x

<=>17x-48x-111=-2x+43

<=>-29x=154

<=> \(x=-\frac{154}{29}\)

-3. (2x + 5) -16 < -4. (3 – 2x)

\(\Leftrightarrow-6x-31< -12+8x.\)

\(\Leftrightarrow-14x< 19\Rightarrow x< -\frac{19}{14}\)

dài quá à :(

1) x - 43 = (35 - x) - 48

=> x + x = 35 - 48 + 43

=> x + x = 30

=> x = 30 : 2

=> x = 15

2) 305 - x + 14 = 48 + (x + 23)

=> 305 - x + 14 = 48 + x + 23

=> -x - x = 48 + 23 - 14 - 305

=> -x - x = -248

=> -x = -248 : 2

=> -x = -124

=> x = 124

3) - (x - 6 + 85) = (x + 51) - 54

=> -x + 6 - 85 = x + 51 - 54

=> -x - x = 51 - 54 + 85 - 6

=> -x - x = 76

=> -x = 76 : 2

=> -x = 38

=> x = -38

4) - (35 - x - 37 - x) = 33 - x

=> -35 + x + 37 + x = 33 - x

=> x + x + x = 33 + 35 - 37

=> x + x + x = 31

=> x = 31 : 3

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

Vì x \(\in\) Z nên không có giá trị x nào thỏa mãn trong câu này.

5) 13 - | x | = | -4 |

=> 13 - |x| = 4

=> |x| = 13 - 4

=> |x| = 9

=> \(\left[{}\begin{matrix}x=9\\x=-9\end{matrix}\right.\)

6) | x | - 3 + 6 = 16

=> |x| = 16 - 6 + 3

=> |x| = 13

=> \(\left[{}\begin{matrix}x=13\\x=-13\end{matrix}\right.\)

7) 35 - | 2x - 1 | = 14

=> |2x - 1| = 35 - 14

=> |2x - 1| = 21

=> \(\left[{}\begin{matrix}2x-1=21\\2x-1=-21\end{matrix}\right.=>\left[{}\begin{matrix}2x=21+1\\2x=-21+1\end{matrix}\right.=>\left[{}\begin{matrix}2x=22\\2x=-20\end{matrix}\right.=>\left[{}\begin{matrix}x=22:2\\x=-20:2\end{matrix}\right.=>\left[{}\begin{matrix}x=11\\x=-10\end{matrix}\right.\)

8) | 3x - 2 | + 5 = 9 - x

=> |3x - 2| = 9 - 5 - x

=> |3x - 2| = 4 - x

=> \(\left[{}\begin{matrix}3x-2=4-x\\3x-2=x-4\end{matrix}\right.=>\left[{}\begin{matrix}3x+x=4+2\\3x-x=-4+2\end{matrix}\right.=>\left[{}\begin{matrix}4x=6\\2x=-2\end{matrix}\right.=>\left[{}\begin{matrix}x=6:4\\x=-2:2\end{matrix}\right.=>\left[{}\begin{matrix}x=\dfrac{6}{4}\\x=-1\end{matrix}\right.\)

Vì x \(\in\) Z nên x = -1.

9) x - ( -25 + 7 ) > 12 - ( 15 - 14 )

=> x - (-18) > 12 - 1

=> x + 18 > 11

=> x > 11 - 18

=> x > -7

10) | 17 + ( x - 15 ) | < 4

=> \(\left[{}\begin{matrix}17+\left(x-15\right)< 4\\17+\left(x-15\right)< -4\end{matrix}\right.=>\left[{}\begin{matrix}x-15< 4-17\\x-15< -4-17\end{matrix}\right.=>\left[{}\begin{matrix}x-15< -15\\x-15< -21\end{matrix}\right.=>\left[{}\begin{matrix}x< -15+15\\x< -21+15\end{matrix}\right.=>\left[{}\begin{matrix}x< 0\\x< -6\end{matrix}\right.=>x< -6\)

11) x2 - 5x = 0

=> x . (2 - 5) = 0

=> x . (-3) = 0

=> x = 0 : (-3)

=> x = 0

12) | x-9 | . (-8) = -16

=> |x - 9| = (-16) : (-8)

=> |x - 9| = 3

=> \(\left[{}\begin{matrix}x-9=3\\x-9=-3\end{matrix}\right.=>\left[{}\begin{matrix}x=3+9\\x=-3+9\end{matrix}\right.=>\left[{}\begin{matrix}x=12\\x=6\end{matrix}\right.\)

13) | 4 - 5x | = 24 với x < hoặc = 0

=> \(\left[{}\begin{matrix}4-5x=24\\4-5x=-24\end{matrix}\right.=>\left[{}\begin{matrix}5x=4-24\\5x=4-\left(-24\right)\end{matrix}\right.=>\left[{}\begin{matrix}5x=-20\\5x=28\end{matrix}\right.=>\left[{}\begin{matrix}x=-20:5\\x=28:5\end{matrix}\right.=>\left[{}\begin{matrix}x=-4\\x=\dfrac{28}{5}\end{matrix}\right.\)

Vì x \(\le\) 0 nên x = -4

14) x . ( x - 2 ) > 0

=> \(\left[{}\begin{matrix}\left\{{}\begin{matrix}x>0\\x-2>0\end{matrix}\right.\\\left\{{}\begin{matrix}x< 0\\x-2< 0\end{matrix}\right.\end{matrix}\right.=>\left[{}\begin{matrix}\left\{{}\begin{matrix}x>0\\x>2\end{matrix}\right.\\\left\{{}\begin{matrix}x< 0\\x< 2\end{matrix}\right.\end{matrix}\right.=>\left[{}\begin{matrix}x>2\\x< 2\end{matrix}\right.\)

15) x . ( x - 2 ) < 0

=> \(\left[{}\begin{matrix}\left\{{}\begin{matrix}x< 0\\x-2>0\end{matrix}\right.\\\left\{{}\begin{matrix}x>0\\x-2< 0\end{matrix}\right.\end{matrix}\right.=>\left[{}\begin{matrix}\left\{{}\begin{matrix}x< 0\\x>2\end{matrix}\right.\\\left\{{}\begin{matrix}x>0\\x< 2\end{matrix}\right.\end{matrix}\right.=>\left[{}\begin{matrix}2>x< 0\left(loại\right)\\0< x< 2\left(chọn\right)\end{matrix}\right.=>0< x< 2\)

16) (x-1) . (y+1) = 5

=> \(\left[{}\begin{matrix}x-1=5\\y+1=1\end{matrix}\right.=>\left[{}\begin{matrix}x=5+1\\y=1-1\end{matrix}\right.=>\left[{}\begin{matrix}x=6\\y=0\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}x-1=1\\y+1=5\end{matrix}\right.=>\left[{}\begin{matrix}x=1+1\\y=5-1\end{matrix}\right.=>\left[{}\begin{matrix}x=2\\y=4\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}x-1=-1\\y+1=-5\end{matrix}\right.=>\left[{}\begin{matrix}x=-1+1\\y=-5-1\end{matrix}\right.=>\left[{}\begin{matrix}x=0\\y=-6\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}x-1=-5\\y+1=-1\end{matrix}\right.=>\left[{}\begin{matrix}x=-5+1\\y=-1-1\end{matrix}\right.=>\left[{}\begin{matrix}x=-4\\y=-2\end{matrix}\right.\)

17) x . ( y +2 ) = -8

=> \(\left[{}\begin{matrix}x=1\\y+2=-8\end{matrix}\right.=>\left[{}\begin{matrix}x=1\\y=-8-2\end{matrix}\right.=>\left[{}\begin{matrix}x=1\\y=-10\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}x=-1\\y+2=8\end{matrix}\right.=>\left[{}\begin{matrix}x=-1\\y=8-2\end{matrix}\right.=>\left[{}\begin{matrix}x=-1\\y=4\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}x=-8\\y+2=1\end{matrix}\right.=>\left[{}\begin{matrix}x=-8\\y=1-2\end{matrix}\right.=>\left[{}\begin{matrix}x=-8\\y=-1\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}x=8\\y+2=-1\end{matrix}\right.=>\left[{}\begin{matrix}x=8\\y=-1-2\end{matrix}\right.=>\left[{}\begin{matrix}x=8\\y=-3\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}x=2\\y+2=-4\end{matrix}\right.=>\left[{}\begin{matrix}x=2\\y=-4-2\end{matrix}\right.=>\left[{}\begin{matrix}x=2\\y=-6\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}x=-2\\y+2=4\end{matrix}\right.=>\left[{}\begin{matrix}x=-2\\y=4-2\end{matrix}\right.=>\left[{}\begin{matrix}x=-2\\y=2\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}x=4\\y+2=-4\end{matrix}\right.=>\left[{}\begin{matrix}x=4\\y=-4-2\end{matrix}\right.=>\left[{}\begin{matrix}x=4\\y=-6\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}x=-4\\y+2=2\end{matrix}\right.=>\left[{}\begin{matrix}x=-4\\y=2-2\end{matrix}\right.=>\left[{}\begin{matrix}x=-4\\y=0\end{matrix}\right.\)

18) xy - 2x - 2y = 0

=> x . (y - 2) - 2y = 0

=> x . (y - 2) - 2y - 4 = -4

=> x . (y - 2) - 2 . (y - 2) = -4

=> (y - 2) . (x - 2) = -4

=> \(\left[{}\begin{matrix}y-2=1\\x-2=-4\end{matrix}\right.=>\left[{}\begin{matrix}y=1+2\\x=-4+2\end{matrix}\right.=>\left[{}\begin{matrix}y=3\\x=-2\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}y-2=-1\\x-2=4\end{matrix}\right.=>\left[{}\begin{matrix}y=-1+2\\x=4+2\end{matrix}\right.=>\left[{}\begin{matrix}y=1\\x=6\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}y-2=2\\x-2=-2\end{matrix}\right.=>\left[{}\begin{matrix}y=2+2\\x=-2+2\end{matrix}\right.=>\left[{}\begin{matrix}y=4\\x=0\end{matrix}\right.\)

hoặc

=> \(\left[{}\begin{matrix}y-2=-2\\x-2=2\end{matrix}\right.=>\left[{}\begin{matrix}y=-2+2\\x=2+2\end{matrix}\right.=>\left[{}\begin{matrix}y=0\\x=4\end{matrix}\right.\)

19) 2x - 5 \(⋮\) x - 1

=> (2x - 2) - (5 - 2) \(⋮\) x - 1

=> 2(x - 1) - 3 \(⋮\) x - 1

Vì 2(x - 1) \(⋮\) x - 1 nên 3 \(⋮\) x - 1

=> x - 1 \(\in\) Ư(3) = {-3; -1; 1; 3}

=> x \(\in\) {-2; 0; 2; 4}

P/s: Mình không bảo đảm là đúng hết nên câu nào sai thì bạn thông cảm nha~

Bài toán 1 : Tìm x nguyên biết.

a. 3 ≤ x – 2 < 5

=>3-2 < x-2 < 5-2

=>1 < x < 3

=>x=1

Vậy x=1

b. 0 ≤ x – 5 ≤ 2

=>0-5 < x-5 < 2-5

=>-5 < x < -3

=>x=-4

Vậy x=-4

Bài toán 2 : Tính hợp lý.

a. 4567 + (1234 – 4567) -4

=4567+1234-4567-4

=(4567-4567)+(1234-4)

=0+1230

=1230

b. 2001 – (53 + 1579) – (-53)

=2001-53-1579+53

=(2001-1579)+(-53+53)

=422+0

=422

c. 35 – 17 + 2017 – 35 + (-2017)

=(35-35)+[2017+(-2017)]-17-35

=0+0-17-35

=0-17-35

=-52

d. 37 + (-17) – 37 + 77

=(37-37)+[-17+77]

=0+60

=60

e. –(-219) + (-219) – 401 + 12

=0-401+12

=-389

f. |-85| – (-3).15

=85+3.15

=85+45

=130

g. 11.107 + 11.18 – 25.11

=11.(107+18-25)

=11.100

=1100

h. 115 – (-85) + 53 – (-500 + 53)

=115+85+53+500-53

=(53-53)+(115+85+500)

=0+700

=700

k. (-18) + (-31) + 98 + |-18| + (-69)

=-18-31+98+18-69

=(-18+18)+(-31-69)+98

=0+(-100)+98

=-100+98

=-2

Bài toán 4 : Tìm x, biêt.

a. 5x – 16 = 40 + x

    5x - x = 40 + 16

    4x = 56

      x = 56 : 4

      x=14

b. 4x – 10 = 15 – x

    4x + x = 15 + 10

    5x = 25

      x = 25 : 5

      x = 5

c. -12 + x = 5x – 20

    -12 + 20 = 5x - x

          8 = 4x

          x = 8 : 4

          x = 2

d. 7x – 4 = 20 + 3x

    7x - 3x = 20 + 4

    4x=24

      x=24:4

      x=6

e. 5x – 7 = – 21 – 2x

    5x + 2x = -21+7

    7x = -14

      x = -14 : 7

      x = -2

f. x + 15 = 7 – 6x

   x + 6x = 7 - 15

   7x = -8

     x = -8/7

g. 17 – x = 7 – 6x

    17 - 7 = -6x + x

    10 = -7x

      x=10/-7

h. 3x + (-21) = 12 – 8x

    3x + 8x = 12 + 21

    11x = 33

        x = 33:11

        x=3 

k. 125 : (3x – 13) = 25

3x-13=125:25

3x-13=5

3x=5+13

3x=18

  x=18:3

  x=6

l. 541 + (218 – x) = 735

  218-x=735-541

  218-x=693

         x=218-693

         x=-475