Вправи: 1203 (1-2)

1203. 1) Розв’яжіть систему рівнянь:

4x + 3y = 0, 4x = –3y, x = –34 y,

5x – 7y = –43; 5x – 7y = –43; 5 ∙(–34y) – 7y = –43│∙ (–4);

x = –34 y, x = –34 y, x = –34 y, x = –34 ∙ 4, x = –3,

15y + 28y = 172; 43y = 172; y = 4; y = 4; y = 4.

Відповідь: (–3; 4);

2) 2x + 9y = –59, 2x = –59 – 9y, x = -59-9y2,

5x – 4y = 38; 5x – 4y = 38; 5 ∙ -59-9y2 – 4y = 38│∙ (–2);

x = -59-9y2, x = -59-9y2, x = -59-9y2,

5(59 + 9y) + 8y = –76; 295 + 45y + 8y = –76; 53y = –371;

x = -59-9y2, x = -59-9•(-7)2, x = 2,

y = –7; y = –7; y = –7.

Відповідь: (2; –7);

3) 3p – 7q = 0, 3p – 7q = 0, 3p – 7q = 0, 3 ∙ 4111 – 7q = 0,

2p + 9p = 41; 11p = 41; p = 4111; p = 4111;

q = 12377, q = 12377,

p = 4111; p = 4111;

Відповідь: (4111; 12377);

4) 6a – 7b = 51, 6a – 7b = 51, 6a – 7b = 51,

2a + 3b = –15; 2a = –15 – 3b; a = -15-3b2;

6 ∙ -15-3b2 – 7b = 51│∙ (–2), 6 ∙ (15 + 3b) + 14b = –102

a = -15-3b2; a = -15-3b2;

90 + 18b + 14b = –102, 32b = –192, b = –6, b = –6,

a = -15-3b2; a = -15-3b2; a = -15-3•(-6)2; a = 1,5

Відповідь: (1,5; –6).