bonjour
5) x = 3 x - 1 9
7 ) 2 x - 4 ( 5 + x ) = ( 4 x - 1 ) ( - 7 )
⇔ 2 x - 20 - 4 x = - 28 x + 7
⇔ - 2 x + 28 x = 7 + 20
⇔ 26 x = 27
⇔ x = 26/27
6 ) A = 50 + 10 ( V - 40)
160 = 50 + 10 V - 400
- 10 V = 50 - 400 - 160
- 10 V = - 510
V = 51
8 ) 2 ( x + 2 + 2 x - 3 ) = 4 ( x + 1 )
2 x + 4 + 4 x - 6 = 4 x + 4
6 x - 4 x = 4 - 4 + 6
2 x = 6
x = 3
9 ) x + 2 x + x + 20 = 180
4 x = 180 - 20
4 x = 160
x = 40
40 ° - 80 ° - 60 °
10) ( 3 x - 2 ) - 3 ( 5 - 2 x ) = 3 ( 2 x + 1 ) + 4
⇔ 3 x - 2 - 15 + 6 x = 6 x + 3 + 4
⇔ 9 x - 6 x = 7 + 17
⇔ 3 x = 24
⇔ x = 8
11 ) trop petit, je ne le lis pas
