[tex]4 {x}^{2} - 12x + 9 = 0[/tex]
[tex]a = 4[/tex]
[tex]b = - 12[/tex]
[tex]c = 9[/tex]
[tex]\Delta = {b}^{2} - 4ac[/tex]
[tex]\Delta = {( - 12)}^{2} - 4 \times 4 \times 9[/tex]
[tex]\Delta = 144 - 144[/tex]
[tex]\Delta = 0 = > \: \exists \: \:x_{1} = x_{2} \: \in \: \mathbb{R}[/tex]
[tex]x_{1}=\frac{-b\pm\sqrt{\Delta}}{2a}[/tex]
[tex]x_{1}=\frac{-( - 12)+\sqrt{0}}{2 \times 4}[/tex]
[tex]x_{1}=\frac{12 + 0}{8}[/tex]
[tex]x_{1}=\frac{12}{8}[/tex]
[tex]x_{1}=\frac{3}{2}[/tex]
[tex]=>x_{1}=x_{2}=\frac{3}{2}[/tex]
