46)
b) 5x - 3y = 9
2x + 7y = 8
- 10x + 6y = - 18
10x + 35y = 40
41y = 22
y = 22/41
2x + 7y = 8
2x + 7(22/41) = 8
2x + 154/41 = 8
82/41x = - 154/41 + 328/41
82x = 174
x = 174/82
x = 87/41
Les solutions sont : (87/41 ; 22/41)
48)
x + y = 83
x - y = 19
x = 83 - y
83 - y - y = 19
83 - 2y = 19
- 2y = 19 - 83
- 2y = - 64
y = 64/2
y = 32
x + y = 83
x + 32 = 83
x = 83 - 32
x = 51
Les solutions sont : (51 ; 32)