Thực hiện phép chia:

a) (x⁴ + 6x² + 8) : (x² + 2);

b) (3x³ – 2x² + 3x – 2) : (x² + 2).

Ta có: 3x(x – 1) + x – 1 = 0

\( \Leftrightarrow \)3x(x – 1) + (x – 1) = 0

\( \Leftrightarrow \)(x – 1)(3x + 1) = 0

\( \Leftrightarrow \left[ \begin{array}{l}x - 1 = 0\\3x + 1 = 0\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}x = 1\\x = \frac{{ - 1}}{3}\end{array} \right.\).

4x² – 25 – (2x – 5)(2x + 7) = 0

\( \Leftrightarrow \)[(2x)² – 5²] – (2x – 5)(2x + 7) = 0

\( \Leftrightarrow \)(2x – 5)(2x + 5) – (2x – 5)(2x + 7) = 0

\( \Leftrightarrow \)(2x – 5)(2x + 5 – 2x – 7) = 0

\( \Leftrightarrow \)(2x – 5)(−2) = 0

\( \Leftrightarrow \)2x – 5 = 0

\( \Leftrightarrow x = \frac{5}{2}\).

Vậy \(x = \frac{5}{2}\).