2)
{9x - 7y = 95
{4x + y = 34
{9x - 7y = 95
{28x + 7y = 238
37x = 333
x = 9
y= 34 - 4x = -2
Ответ: (9; -2)
3)
{3x - 5y = 23
{2x + 3y = 9
{9x - 15y = 69
{10x + 15y = 45
19x = 114
x = 6
y = (9-2x)/3 = -1
Ответ: (6; -1)
4)
{6x + 5y = 0
{2x + 3y = -8
{6x + 5y = 0
{-6x - 9y = 24
-4y = 24
y = -6
x = (-5y)/6 = 5
Ответ: (5; -6)
-9а+8=-10а-2
-9а+10а=-2-8
а=-10