Question

What is the line of symmetry of the parabola y=x2+6x-9?

x=6
x=-9
x=-3

Answer 1

In the given parabola
`y=x^2+6x-9` the line of symmetry is the axis x = -3

Explanation:

Here, the given equation of the parabola is :
`y=x^2+6x-9`

Now, in the Standard Form of the Parabolic Equation:
`y=ax^2+bx+c`,

The axis of symmetry is a vertical line x = −b / 2 a .

Now, here comparing the given parabolic equation with teh standard form, we get :

a = 1 , b = 6 and c = -9

So, the axis of symmetry =
`-(b)/(2a)  =- (6)/(2(1)) =  -3`

Hence, here in the given parabola
`y=x^2+6x-9` the line of symmetry is the axis x = -3.