Question

Tong tat ca cac gia tri cua x thoa man \(x^3+5\times x^2+3x-9=0\)

Answer 1

x³ + 5x² + 3x - 9 = 0

x³ + 3x² + 2x² + 6x - 3x - 9 = 0

x²(x + 3) + 2x(x + 3) - 3(x + 3) = 0

(x + 3)(x² + 2x - 3) = 0

(x + 3)(x² - x + 3x - 3) = 0

(x + 3)[x(x - 1) + 3(x - 1)] = 0

(x + 3)²(x - 1) = 0

x \(\in\) {-3;1}

Tổng tất cả giá trị x là - 3 + 1 = - 2