1. (1;-1)
2. (1;3)
3. (11;-34)
4. (2/3; -1)
Пошаговое объяснение:
1. x - 3y = 4
2x - y = 3
x = 4 + 3y
2(4 + 3y) - y = 3
x = 4 + 3y
5y = -5
x = 4 - 3 = 1
y = -1
2. 4x - y = 1
5x + 3y = 14
y = 4x - 1
5x + 3(4x - 1) = 14
y = 4x - 1
17x = 17
y = 3
x = 1
3. 7a + 2b = 9
3a + b = -1
7a + 2(-1 - 3a) = 9
b = -1 - 3a
a = 11
b = -1 - 33 = -34
4. 3x + 4y = -2
6x - 7y = 11
3x = -2 - 4y
2(-2 - 4y) - 7y = 11
3x = - 2 - 4y
-15y = 15
x = 2/3
y = -1
