1) A = - 4/7 x 5/2 - 3/2 x 7/9 A = - 20/14 - 21/18 A = - 20 x 9 / 14 x 9 - 21 x 7 / 18 x 7 A = - 180/126 - 147/126 A = - 327/126
B = 20/9 : 35/27 B = 20/9 x 27/35 B = 540/315 B = 45 x 12 / 45 x 7 B = 12/7
C = (4/9 + - 7/15) : (- 7/5 - 1/6) C = (4 x 5 / 9 x 5 - 7 x 3 / 15 x 3) : (- 7/5 - 1/6) C = (20/45 - 21/45) : (- 7 x 6 / 5 x 6 - 1 x 5 / 6 x 5) C = - 1//45 : (- 42/30 - 5/30) C = - 1/45 x - 30/47 C = 30/2115 C = 15 x 2 / 15 x 141 C = 2/141
D = 3/2 - 1/4 3/8 D = 3 x 2 / 2 x 2 - 1/4 3/8 D = 6/4 - 1/4 3/8 D = 5/4 : 3/8 D = 5/4 x 8/3 D = 40/12 D = 4 x 10 / 4 x 3 D = 10/3
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Bonjour,1)
A = - 4/7 x 5/2 - 3/2 x 7/9
A = - 20/14 - 21/18
A = - 20 x 9 / 14 x 9 - 21 x 7 / 18 x 7
A = - 180/126 - 147/126
A = - 327/126
B = 20/9 : 35/27
B = 20/9 x 27/35
B = 540/315
B = 45 x 12 / 45 x 7
B = 12/7
C = (4/9 + - 7/15) : (- 7/5 - 1/6)
C = (4 x 5 / 9 x 5 - 7 x 3 / 15 x 3) : (- 7/5 - 1/6)
C = (20/45 - 21/45) : (- 7 x 6 / 5 x 6 - 1 x 5 / 6 x 5)
C = - 1//45 : (- 42/30 - 5/30)
C = - 1/45 x - 30/47
C = 30/2115
C = 15 x 2 / 15 x 141
C = 2/141
D = 3/2 - 1/4
3/8
D = 3 x 2 / 2 x 2 - 1/4
3/8
D = 6/4 - 1/4
3/8
D = 5/4 : 3/8
D = 5/4 x 8/3
D = 40/12
D = 4 x 10 / 4 x 3
D = 10/3
2)
x² - 2x = - 5x/3
1/3² - 2 * 1/3 = - 5 * 1/3 : 3
1/9 - 2/3 = - 5/3 : 3
1/9 - 2 x 3 / 3 x 3 = - 5/3 x 1/3
1/9 - 5/9 = - 5/9
- 4/9 ≠ - 5/9 - L'égalité est fausse