1){ 2x-3y =11; 4x+5y =-11.
5(2x-3y) +3(4x+5y) =5*11+ 3(-11);
22x=22 ;
x=1;
yvvbbb
2*1 -3y =11;
-3y =9;
y = - 2;
ответ: (1;-2).
2) {3x +7y =2; 2x -5y =1.
{ 3x+7y =2 ||*5|| ;2x -5y =1 ||*7|| .
5(3x+7y) +7(2x -5y) =5*2 +7*1;
29x =17;
x=17/29;
2(3x+7y) +(2x -5y)*(-3) =2*2 +1(-3);
29y =1;
y=1/29.
ответ: (17/29; 1/29)
3) {(1/5)*(x+y) =2; 1/2(x-y) =1. ⇔{x+y =10; x-y =2.
(x+y) +(x -y) =10 +2;
2x=12;
x= 6;
(x+y)-(x-y) =10 -2;
2y =8;
y =4.
(6,4)