Question

What is the vertical of the graph of this equation y=3x^2-12x-9

Answer 1

The graph of the parabola is represented in the attached diagram.

The vertical axis of symmetry is the line with equation

`x=-(b)/(2a)=-(-12)/(2\cdot 3)=2.`

This axis passes through the parabola vertex with coordinates:

• x=2;
• 
  `y=3\cdot 2^2-12\cdot 2-9=12-24-9=-21.`

Answer: vertical axis of symmetry is line x=2.