bonsoir svvvvvvvvp aidez moi ex de maths et merci

Réponse:

1) 3x+4=2x+9

3x-2x=9-4

X=5

2)2x+3=3x-5

2x-3x=-5-3

-x=2

X=-2

3)5x-1=7x+5

5x-7x=5+1

-2x=6

-x=3

X=-3

4)4x+3-(x+1)+5=5x+7

4x+3-x-1+5=5x+7

4x-x-5x=7-3+1-5

-2x=0

X=0

Explications étape par étape:

3x + 4 = 2x + 9

<=> 3x - 2x = 9 - 4

<=> x = 5

2x + 3 = 3x - 5

<=> 3 + 5 = 3x - 2x

<=> 8 = x

5x - 1 = 2x + 4

<=> 5x - 2x = 4 + 1

<=> 3x = 5

<=> x = 5/3

3x + 1 = 7x + 5

<=> 1 - 5 = 7x - 3x

<=> - 4 = 4x

<=> x = - 4/4

<=> x = - 1

4x + 3 - ( x + 1) + 5 = 5x + 7

<=> 4x + 3 - x - 1 + 5 = 5x + 7

<=> 3x + 7 = 5x + 7

<=> 7 - 7 = 5x - 3x

<=> 0 = 2x

<=> x = 0

2x + 1 - (2 + x) - 7 = 3x + 7

<=> 2x + 1 - 2 - x - 7 = 3x + 7

<=> x - 8 = 3x + 7

<=> - 8 - 7 = 3x - x

<=> - 15 = 2x

<=> x = - 15/2 ou x = - 7.5

5(x - 1) + 3(2 - x) = 0

<=> 5x - 5 + 6 - 3x = 0

<=> 2x + 1 = 0

<=> 2x = -1

<=> x = - 1/2

7(x + 4) - 3(x + 2) = x + 7

<=> 7x + 28 - 3x - 6 = x + 7

<=> 4x + 22 = x + 7

<=> 4x - x = 7 - 22

<=> 3x = - 15

<=> x = - 5

2(x - 1) - 3(x + 1) = 4(x -2)

<=> 2x - 2 - 3x - 3 = 4x - 8

<=> - x - 5 = 4x - 8

<=> - 5 + 8 = 4x + x

<=> 3 = 5x

<=> x = 3/5

5(3x - 1) - (1 - 2x) = 3(5x - 2)

<=> 15x - 5 - 1 + 2x = 15x - 6

<=> 17x - 6 = 15x - 6

<=> 17x - 15x = - 6 + 6

<=> 2x = 0

<=> x = 0

(x + 2)(x + 1) = (x + 4)(x - 5)

<=> x² + x + 2x + 2 = x² - 5x + 4x - 20

<=> x² + 3x + 2 = x² - x - 20

<=> 3x + x = - 20 - 2

<=> 4x = - 22

<=> x = - 11/2