Tìm x biết (2x – 3)2 – 4x2 + 9 = 0 A. x=1/2

* Hướng dẫn giải

$$\begin{gathered} {(2x – 3)}^2 – 4x^2 + 9 = 0 \\ \iff {(2x – 3)}^2 – (4x^2 – 9) = 0 \\ \iff {(2x – 3)}^2 – ({\left(2x\right)}^2 – 3^2) = 0 \\ \iff {(2x – 3)}^2 – (2x – 3)(2x + 3) = 0 \end{gathered}$$

ó (2x – 3)(2x – 3 – 2x – 3) = 0

ó (2x – 3)(-6) = 0

ó 2x – 3 = 0

ó$x=\frac{3}{2}$

Đáp án cần chọn là: C