Answer:
Step-by-step explanation:
[tex]3x^2-24x=-12\qquad\text{divide both sides by 3}\\\\x^2-8x=-4\\\\x^2-2(x)(4)=-4\qquad\text{add}\ 4^2\ \text{to both sides}\\\\x^2-2(x)(4)+4^2=-4+4^2\qquad\text{use}\ (a-b)^2=a^2-2ab+b^2\\\\(x-4)^2=-4+16\\\\(x-4)^2=12\to x-4=\pm\sqrt{12}\\\\x-4=\pm\sqrt{4\cdot3}\\\\x-4=\pm\sqrt4\cdot\sqrt3\\\\x-4=\pm2\sqrt3\qquad\text{add 4 to both sides}\\\\x=4\pm2\sqrt3[/tex]