Вправи
Вправи: 787 (1-8)
Готова відповідь до завдання 787 (1-8) з ГДЗ Алгебра 8 клас Тарасенкова.
Алгебра, 8 клас · Вправи
Текстова відповідь
787. Скориставшись теоремою Вієта, розв’яжіть квадратне рівняння:
1) x2 + 3x – 4 = 0.
x1 + x2 = –3; x1 • x2 = –4;
x1 = –4; x2 = 1.
2) x2 – 6x – 16 = 0.
x1 + x2 = 6; x1 • x2 = –16;
x1 = –2; x2 = 8.
3) x2 + 7x – 30 = 0
x1 + x2 = –7; x1 • x2 = –30;
x1 = 3; x2 = –10.
4) x2 – 10x + 16 = 0.
x1 + x2 = 10; x1 • x2 = 16;
x1 = 2; x2 = 8.
5) x2 – 12x + 11 = 0.
x1 + x2 = 12; x1 • x2 = 11.
x1 = 1; x2 = 11.
6) x2 – 9x + 8 = 0.
x1 + x2 = 9; x1 • x2 = 8.
x1 = 1; x2 = 8.
7) x2 + x – 12 = 0.
x1 + x2 = –1; x1 • x2 = –12.
x1 = –4; x2 = 3.
8) x2 – 15x + 26 = 0;
x1 + x2 = 15; x1 • x2 = 26.
x1 = 2; x2 = 13.
9) x2 + 5x + 4 = 0;
x1 + x2 = –5; x1 • x2 = 4;
x1 = –1; x2 = –4.
10) x2 + 6x + 5 = 0;
x1 + x2 = –6; x1 • x2 = 5;
x1 = –1; x2 = –5.
11) x2 + x – 2 = 0.
x1 + x2 = –1; x1 • x2 = –2.
x1 = –2; x2 = 1.
12) x2 + 25x + 100 = 0;
x1 + x2 = –25; x1 • x2 = 100;
x1 = –5; x2 = –20.
13) x2 – 9x – 10 = 0.
x1 + x2 = 9; x1 • x2 = –10.
x1 = –1; x1 = 10.
14) x2 + 8x + 7 = 0.
x1 + x2 = –8; x1 • x2 = 7.
x1 = –1; x2 = –7.
15) x2 – 3x + 2 = 0;
x1 + x2 = 3; x1 • x2 = 2.
x1 = 1; x2 = 2.