How do I find the axis of symmetry without the parabola equation?

[Niaboc67]

Homework Statement

The Attempt at a Solution

I would guess it is -b/2a but I have gotten this incorrect. Maybe I have to figure out what the parabola equation is and apply it into the axis of symmetry. Assuming that is correct how would I find that?

Thanks[/B]

 

[Dick]

Homework Statement

The Attempt at a Solution

I would guess it is -b/2a but I have gotten this incorrect. Maybe I have to figure out what the parabola equation is and apply it into the axis of symmetry. Assuming that is correct how would I find that?

Thanks[/B]

You should be able to guess it like you guessed the other answers. Do you know what axis of symmetry means visually?

 

[Niaboc67]

Isn't it the line which divide the parabola into two even parts. So the line that goes directly down the middle.

 

[Dick]

Isn't it the line which divide the parabola into two even parts. So the line that goes directly down the middle.

Right. What is that line?

 

[Niaboc67]

Look to be the y-axis itself?

 

[Dick]

Look to be the y-axis itself?

Right again. Now what's an EQUATION for that line?

 

[Niaboc67]

Oh I just looked up some information on this and it looks like x=0 would create a completely vertical line. Is this correct?

 

[Dick]

Oh I just looked up some information on this and it looks like x=0 would create a completely vertical line. Is this correct?

Perfectly correct.

 

[Niaboc67]

Awesome! Thank you for your assistance!

 

[HallsofIvy]

I would just like to add that your initial answer, "- 2a/b", makes no sense because there is no "a" and no "b" in the problem! I assume that was a general formula but you were not asked for a general formula, you were asked for an answer specific to this problem.