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bonjour help me pour demain
resoudre ces equations :
(x-4)(x+1)-(x+7)(x-3)=-7x+17
et
(x-3)/4 + (2x-8)/5 - 1/3 =0


Répondre :

bonsoir

x² + x - 4 x - 4  - ( x² - 3 x + 7 x - 21) = - 7 x + 17
x² - 3  x - 4  - x² + 3  x - 7 x + 21 = - 7 x + 17
- 7 x + 17 = - 7 x + 17
- 7 x + 7 x = 17 - 17
0 x = 0 

( x - 3)/4 + ( 2 x - 8)/5 - 1/3 = 0
(5 x - 15)/ 20 + ( 8 x - 32)/20  - 1/3 = 0
 13 x /20 - 1/3 = 0
39 x /60 - 20/60 = 0
39 x = 20
x = 20/39 

Bonsoir :

(x - 4)(x + 1) - (x + 7)(x - 3) = -7x + 17
(x² + x - 4x - 4) - (x² - 3x + 7x -21) +7x - 17 = 0
x² - 3x - 4 - x² + 3x - 7x +21 + 7x -17 =0
x² - x² -3x - 3x + 7x - 7x -4 + 21 - 17 = 0
0 + 17 -17 = 0
0 = 0

(x-3)/4 + (2x-8)/5 - 1/3 = 0
5(x-3)/4×5 + 4(2x-8)/5×4 - 1/3 = 0
5x-15/20 + 8x-32/20 - 1/3 = 0
3(5x-15)/20×3 + 3(8x-32)/20×3 - 20×1/3×20 = 0
15x-45/60 + 24x-96/60 - 20/60 = 0
15x-45 + 24x-96 - 20 = 0

Et continu de calcule

J’espère t'avoir t'aider