Question

$9X^2-12X+4=0$ X=?

Answer 1

$9x^2-12x+4=0\\ (3x-2)^2=0\\ 3x-2=0\\ 3x=2\\ x=\dfrac{2}{3}$

Answer 2

$9x^2-12x+4=0$ 

$(3x)^2-2\cdot 2\cdot3x+2^2=0$

$(3x-2)^2=0, but...(3x-2)^2 \geq 0$ , ∨ x∈R

$So, (3x-2)^2=0$

$3x-2=0$ ⇒ $3x=2$ ⇒ $\boxed { x= \frac{2}{3} }$