N° 60
E = 9 - (2x -1)²
Développement
E = 9 - (4x² -4x +1)
E = 9 - 4x² +4x -1
E = -4x² +4x +8
Factorisation ( différence de 2 carrés)
(3 +2x -1)(3 -2x +1)
(2x +2)( -2x +4)
Pour x = 1/3
E = ( 2/3 +2)( -2/3 +4)
E = (2/3 + 6/3)( -2/3 + 12/3)
E = 3/3 x 11/3
E = 1 x 11/3 = 11/3
N°61
E = (3x+2)² - (3x+2)(x+7)
E = (9x²+12x +4) - ( 3x² + 21x +2x +14)
E = 9x² +12x +4 - 3x² -21x -14
E = 6x² - 9x -10
factorisation
(3x+2)(3x+2) - (x+7)
(3x+2)(3x+2-x -7)
E = (3x+2)(2x -5)
Pour x = 1/2
E = (3/2 +2)( 2/2 -5)
E = (3/2 + 4/2) ( 2/2 - 10/2)
E = 7/2 x -8/2 = - 56/2 = - 28
N°6
5(y -1) +2 = 7y -3
5y -5 +2 = 7y -3
5y -7y = -3 -2 +5
-2y = 0
y = 0
N°7
(3a-2) - 4(1 -2a) = 5a -7
3a -2 -4 +8a = 5a -7
3a +8a -5a = -7 +2 +4
6a = -1
a = -1/6
N°8
tu mets tout sous dénominateur 16
6x - 14 -5x -1 = 12 - 8x
6x -5x +8x = 12 +1 +14
9x = 27
x = 27/9
x = 3
