Question

1. Разложите на множители квадратный трёхчлен:
1) х² + х - 30
2)2x²-7x-9​

Answer 1

${x}^{2} - x - 30 \\ {x}^{2} - x - 30 = 0 \\d = 1 - 1 \times 4 \times ( - 30) = 121 \\ x1 = \frac{1 - 11}{2} = - 5 \\ x2 = \frac{1 + 11}{2} = 6 \\ (x + 5)(x - 6)$$2 {x}^{2} - 7x - 9 \\ 2 {x}^{2} - 7x - 9 = 0 \\ d = 49 - 4 \times 2 \times ( - 9) = 121 \\ x1 = \frac{7 - 11}{4} = - 1 \\ x2 = \frac{7 + 11}{4} = 4.5 \\ 2(x + 1)(x - 4.5) = (x + 1)(2x - 9)$