{ (x+7)/3 - (y-8)/5 =3 |*15
{ (x+5)/4 + (y+9)/3 =5 |*12
{5(x+7) - 3(y-8)= 3*15
{3(x+5) + 4(y+9) = 5*12
{5x+35 - 3y + 24= 45
{3x + 15 + 4y + 36 = 60
{ 5x -3y = 45 -59
{ 3x +4y = 60 -51
{5x - 3y = -14 |*4
{3x +4y = 9 |*3
{20x -12y = -56
{9x +12y = 27
метод сложения:
20х -12у +9х +12у = -56 +27
29х = -29
х=-1
5* (-1) -3у =-14
-5-3у = -14
-3у = -14 +5
-3у = -9
у= (-9)/(-3)
у= 3
ответ : (-1 ;3)
{(x+9)/3 - (y+8)/6 = 3 | * 6
{(x+11)/7 + (y+6)/2 = 4 |*14
{ 2(x+9) - (y +8) = 18
{2(x+11) + 7(y + 6) = 56
{2x + 18 - y - 8 = 18
{2x + 22 + 7y +42=56
{2x-y = 18 - 10
{2x + 7y = 56 - 64
{2x - y = 8 ⇒ y = 2x - 8
{2x +7y = -8
метод подстановки
2х + 7(2х-8) = -8
2х + 14х - 56 = -8
16х = -8+56
х=48/16
х=3
у=2*3-8
у= 6-8
у=-2
ответ : (3 ; - 2)