What are it's line of symmetry?

4x^2+y^2=9

my answer is

it has 2 lines of symmetry, the x and y axis

You are correct,

you are looking at an ellipse with centre (0,0)

To determine the lines of symmetry for the equation 4x^2 + y^2 = 9, we can start by rearranging the equation into a more familiar form. Let's isolate the x and y terms:

4x^2 + y^2 = 9

Divide both sides by 9:

(4x^2)/9 + (y^2)/9 = 1

Now, we can rewrite the equation using the variables a^2 and b^2, which will reveal the standard equation for an ellipse:

(x/a)^2 + (y/b)^2 = 1

Comparing this equation to our rearranged equation, we can determine the values of a and b:

a = √(9/4)
b = √(9)

Now, we can identify the lines of symmetry. For an ellipse, the lines of symmetry are the x and y axes. In this case, since a > b, the major axis of the ellipse coincides with the x-axis, while the minor axis aligns with the y-axis.

Therefore, the equation 4x^2 + y^2 = 9 has the x-axis and y-axis as its lines of symmetry.