Correction exercices semaine du mercredi 27 mai ex 18 p 78 5x ? 8 ...

Correction exercices semaine du mercredi 27 mai ex 18 p 78
|5x - 8+8 = 4+8 |3x-6+6 = 8 - 3x+6 |6 - 2(3x + 4) = 8x - ( 5|
|5x/5 = 12/5 |3x +3x = 14 - 3x +3x |- 6x) |
|x = 12/5 |6x/6 = 14/6 |6 - 6x - 8 = 8x - 5 + 6x|
| |x = 14/6 = 7/3 | |
| | |- 2 - 6x - 14x = 14x - 5|
| | |-14x |
| | |-2 - 20x + 2 = -5 + 2 |
| | |-20x/-20 = -3/-20 |
| | |x = 3/20 | Ex 22 p 78
3 - 2(5x - 3) = 4x - (3 - 2x)
3 - 10x + 6 = 4x - 3 +2x
9 - 10x - 6x = 6 x - 3 - 6x
9 -16x -9 = -3 - 9
-16x/-16 = -12/-16
x = -12/-16 = 12/16 = ¾ ex 23 p 78
|(2x - 1) + (5 - 3x) = 0 |(2x - 1)(5 - 3x) = 0 |
|2x - 1 + 5 - 3x = 0 |Par propriété : « un produit de |
|-x + 4 - 4 = 0 - 4 |facteurs est nul ssi l'un des |
|-x = - 4 donc x = 4 |facteurs est nul » |
| |2x - 1 = 0 ou 5 - 3x = 0 |
| |x = ½ x = -5/-3 |
| |= 5/3 | Ex 50 p 80
| X - 3 + 3 = |7 + x - 7 = 0 |5x/5 = -2/5 |x/5x5 = -8x5 |3x/3 = 0/3 |
|0 + 3 |- 7 |x = -2/5 |x = -40 |x = 0 |
|x = 3 |x = - 7 | | | | Ex 51 p 80
|3x + 2 = 0 |4 - 5x - 4 = 0 - 4 |7x + 8 - 8 = 0-8 |
|3x + 2 -2 = 0 - 2 |-5x/-5 = -4/-5 |7x / 7 = -8/7 |
|3x/3 = -2/3 |x = - 4/-5 = 4/5 |x=-8/7 |
|x = -2/3 | | |
|9x - 4 + 4 = 0+4 |5x + 4 - 4 = 4-4 | |
|9x/9 = 4/9 |5x/5 = 0/5 | |
|x = 4/9 |x = 0 | | Ex 52 p 80
|3x - 2 +2 = 11 + 2 |5 - 7x - 5 = - 11 - 5 |
|3x/3 = 13/3 |- 7x/-7 = -16/-7 |
|x = 13/3 |x = 16/7 |
|6x - 4x = 4x - 9 - 4x | 6 - 8x - 6 = 16x - 6 |
|2x/2 = -9/2 |- 8x - 16x = 16 x - 6 - 16x |
|x = -9/2 |-24x/-24 = - 6/-24 |
| |x = 6/24 = 1/4 | Ex 53 p 80
|4x - 7 + 7 = 3x + 8 + 7 |7 - 8x - 11x - 7= 11x - 5 - 11x - 7 |
|4x - 3x = 3x + 15 - 3x |-19x = - 12 |
|x = 15 |x = 12/19 |
| 9X + 5 + 3x - 5 = 4 - 3x - 5 + 3x |- 2x + 5 - 5 + 8x= -8x + 10 - 5 + 8x |
|12x = - 1 |6x = 5 |
|x = -1/12 |x = 5/6 | Ex 54p80
|3 - (5x + 1 ) = 8x + ( 4 -2x) | 8 - 3(2x - 4) = 5x - ( x +1) |
|3 - 5x - 1 = 8x + 4 - 2x |8 - 6x + 12 = 5x - x - 1 |
|2 - 5x - 6x - 2= 6x + 4 - 6x - 2 |20 - 6x - 20 - 4x = 4x - 1 - 20 - 4x |
|-11x = 2 |- 10x = - 21 |
|x = -2/11 |x = -21/-10 = 21/10 | Ex 55 p 80
|8 + (3x - 2) = 5x - (3x - 5) |4(2x - 6) - 8 = 5 - (x - 7) |
|8 + 3x - 2 = 5x - 3x + 5 |8x - 24 - 8 = 5 -x + 7 |
|6 + 3x - 6 - 2x = 2x + 5 - 6 -2x |8x - 32 + x + 32 = 12 - x + x + 32 |
|x = -1 |9x = 44 |
| |x = 44/9 | Ex 56 p80
x + 1 + 7x - 4 = 4(8x + 3)
8x - 3 + 3 - 32x = 32x + 12 - 32x + 3
-24x = 15
x = -15/24 = -5/8 ex 57 p 80
|X/8 = 5/7 |2x-3/5 = 6/7 |4x - 3 / 2 = 2x + 5/3 |
|x = 5x8/7 |7(2x - 3) = 5x6 |3(4x - 3) = 2(2x + 5) |
|x = 40/7 |14x - 21+21 = 30+21 |12x - 9- 4x + 9 = 4x + 10 - |
| |14x /14 = 51/14 |4x + 9 |
| |x = 51/14 |8x = 19 |
| | |x = 19/8 |
Ex 60 p 80
Pour tout l'exercice on utilise la propriété : « un produit de facteurs est
nul ssi l'un des facteurs au moins est nul »
|(x-5)(6+x) = 0 |(2x+7)(9-x) = 0 |
|x-5 = 0 ou 6+x = 0 |2x+7 = 0 ou 9-x=0 |
|x = 5 x = -6 |x = -7/2 x = 9 |
|Les solutions de l'équation sont x=5 |Les solutions de l'équation sont x = |
|et x=-6 |-7/2 et x = 9 |
|(4x-6)(9x+5)=0 |(2x-7)(8x+6)=0 |
|4x - 6 =0 ou 9x+5=0 |2x - 7 = 0 ou 8x +6 = 0 |
|x=6/4 x = -5/9 |x = 7/2 x = -6/8 |
|Les solutions de l 'équation sont x |Les solutions de l'équation sont |
|=6/4 et x =-5/9 |x=7/2 et x = -6/8 |