Вправи 888 - 1000 » 966 (г-ґ)

г) 3x(5x + 3) = 2x(6x + 5) + 2; 15х2 + 9х = 12х2 + 10х + 2; 15x2 + 9x – 12x2 – 10x – 2 = 0; 3x2 – x – 2 = 0; x = (1 ± √(1+24))/6 = (1 ± 5)/6; x1 = (1+5)/6 = 1; x2 = (1-5)/6 = –2/3. Відповідь: 1; –2/3. ґ) (2x – 8)(Зx + 1) = (4x – 12)(x – 2) + 8; 6x2 + 2х – 24x – 8 = 4x2 – 8x – 12x + 24 + 8; 6х2 – 22x – 8 – 4х2 + 20x – 32 = 0; 2x2 – 2x – 40 = 0; x2 – x – 20 = 0; x = (1 ± √(1+80))/2 = (1 ± 9)/2; x1 = 5; x2 = –4. Відповідь: 5; –4.