Répondre :
Bonjour,
1)
a) M = 2/5 - 4/3 + 7/2
M = (2 x 6) / (5 x 6) - (4 x 10) / (3 x 10) + (7 x 15) / (2 x 15)
M = 12/30 - 40/30 + 105/30
M = 77/30
b) N = 2/3 - 5/3 x 3/2
N = 2/3 - 15/6
N = (2 x 2) / (3 x 2) - 15/6
N = 4/6 - 15/16
N = - 11/6
c) L = (- 7/4 + 1/2) : (2/7 + 1/4)
L = [- 7/4 + (1 x 2) / (2 x 2)] : [(2 x 4) / (7 x 4) + (1 x 7) / (4 x 7)]
L = (- 7/4 + 2/4) : (8/28 + 7/28)
L = - 5/4 : 15/28
L = - 5/4 x 28/15
L = - 140/60
L = (20 x - 7) /(20 x 3)
L = - 7/3
d) P = - 28/5 : - 21
P = - 28/5 x - 1/21
P = 28/105
P = (7 x 4) / (7 x 15)
P = 4/15
2) Inverse de M = 30/77
3) Opposé de M = - 77/30
4)
a) M - N
= 77/30 - (- 11/6)
= 77/30 + (11 x 5) / (6 x 5)
= 77/30 + 55/30
= 132/30
= (6 x 22) / (6 x 5)
= 22/5
b) N x L
= - 11/6 x - 7/3
= 77/18
c) M : N
= 77/30 : - 11/6
= 77/30 x - 6/11
= - 462/330
= (66 x - 2) / (66 x 7)
= - 2/7
5)
a) 2/3 (x - 1) =- 1/5 (x + 3) - 1/2
2/3x - 2/3 = - 1/5x - 3/5 - 1/2
20/30x - 20/30 = - 6/30x - 18/30 - 15/30
20x - 20 = - 6x - 18 - 15
20x + 6x = - 18 - 15 + 20
26x = - 13
x = - 13/26
x =- 1/2
b) (2x + 1) / 2 - x/3 = (x - 5) / 6
(6x + 3) / 6 - 2x/6 = (x - 5) / 6
6x + 3 - 2x = x - 5
6x - 2x - x = - 5 - 3
3x = - 8
x = - 8/3
Réponse :
Explications étape par étape
Bonjour
Calculer :
M = 2/5 - 4/3 + 7/2
M = 12/30 - 40/30 + 105/30
M = 77/30
N = 2/3 - 5/3 x 3/2
N = 2/3 - 3/3 x 5/2
N = 2/3 - 5/2
N = 4/6 - 15/6
N = -11/6
L = (-7/4 + 1/2) : (2/7 + 1/4)
L = (-7/4 + 2/4) : (8/28 + 7/28)
L = (-5/4) : (15/28)
L = -5/4 x 28/15
L = -5/15 x 28/4
L = -1/3 x 7
L = -7/3
P = (-28/5)/-21
P = -28/5 x -1/21
P = -28/21 x -1/5
P = 4/3 x 1/5
P = 4/15
2) inverse de M : 30/77
3) opposé de M : -77/30
4) calculer :
M - N = 77/30 - (-11/6) = 77/30 + 55/30 = 132/30 = (22 x 6)/(5 x 6) = 22/5
N x L = -11/6 x -7/3 = 77/18
M / N = (77/30) / (-11/6) = 77/30 x -6/11 = -77/11 x 6/30 = -7 x 1/5 = -7/5
5) résoudre :
2/3(x - 1) = -1/5(x + 3) - 1/2
2/3 x - 2/3 = -1/5 x - 3/5 - 1/2
2/3 x + 1/5 x = 2/3 - 3/5 - 1/2
10/15 x + 3/15 x = 20/30 - 18/30 - 15/30
13/15 x = -13/30
x = -13/30 * 15/13
x = -13/13 * 15/30
x = -1/2
(2x + 1)/2 - x/3 = (x - 5)/6
[3(2x + 1)]/6 - 2x/6 = (x - 5)/6
6x + 3 - 2x = x - 5
4x - x = -3 - 5
3x = -8
x = -8/3
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