Tìm x biết: (3x - 2)^2 - 9x^2 + 4 = 0

Ta có: 3x−22−9x2+4=0

            ⇔3x−22−9x2−4=0

             ⇔3x−22−3x−23x+2=0

                   ⇔3x−23x−2−3x−2=0

                   ⇔−43x−2=0⇔3x−2=0⇔x=23

Vậy x=23