Π/3+πn<x<π/2+πn,n∈z
x∈(<span>π/3+πn;π/2+πn,n∈z)</span>
1) 4x - y = 7
y = 4x - 7
y(0) = -7; y(7/4) = 4*7/4 - 7 = 0
Решения: (0; -7); (7/4; 0)
2) -2x + y = 11
y = 2x + 11
y(0) = 11; y(-11/2) = 2(-11/2) + 11 = 0
Решения: (0; 11); (-11/2; 0)
3) 5x - 3y = 15
y = (5x - 15)/3 = 5x/3 - 5
y(0) = -5; y(3) = 5*3/3 - 5 = 0
Решения: (0; -5); (3; 0)
У=8-2х
3х+4(8-2х)=7
3х+32-8х=7
-5х=-25
х=5
у=8-2*5
у=-2
Ответ: 5;-2.