Question

Tìm x:

(2x-1)(4x^2+2x+1)=x(x-8)

Answer 1

        (2x - 1)(4x² + 2x + 1) = x(x-8)

<=>                   (2x)³ - 1³ = x² - 8x

<=>     (8x³ - x²) + (8x - 1) = 0

<=>     x²(8x - 1) + (8x - 1) = 0Σ

<=>            (x² + 1)(8x - 1) = 0

x² + 1 = 0 => x² = -1 ( vô lý )8x - 1 = 0 => 8x = 1 => x = 0,125