# math

posted by .

Find the foci for the equation of an ellipse:
2x^2 + 8x + y^2 + 4 = 0

• math -

2(x^2 + 4x + 4) + y^2 = -4 + 8 = 4
2(x+2)^2 + y^2 = 4
(x+2)^2/2 + y^2/4 = 1
[(x+2)/sqrt2]^2 + (y/2)^2 = 1

The ellipse center is at(-2, 0)
The semiminor axis length is sqrt2
The semimajor axis length is 2

The foci along the vertical axis at x = -2, at +/- c, where c = sqrt (4 - 2) = sqrt2

## Similar Questions

1. ### Math

Find an equation for the ellipse. center:(3,2) a=3c Foci:(1,2)(5,2) h=3 k=2 I do not know where to start.
2. ### Math/Conics

Find the center, vertices, and foci of the ellipse with the following equation: x^2/9+y^2/16=1
3. ### maths

Given that the ellipse x^2/a^2 + y^2/b^2 =1 has foci at(+/-ae,0)where e is the eccentricity and b^2=a^2(1-e^2),find the coordinates of the foci and the value of e^2 for the ellipse X^2+4y^2 =16
4. ### Algebra

1. What is the equation an ellipse with foci at (0, ±2 √10 ) and x-intercept at (9, 0)?
5. ### pre-calculus

the foci of an ellipse are (0,2) (0,-2) and the eccentricity is 1/2. determine the equation of the ellipse. write your answer in standard form.
6. ### math

let equation of an ellipse be x^2+4y^2+6x-8y+9=0 a. Find the standard form of the ellipse b. Find the center c. Find the vertices d. Find the foci e. Find the eccentricity
7. ### math

Find the center, vertices, and foci of the ellipse with equation 3x^2 + 8y^2 = 24.
8. ### math

The equation 4x^2 +9y^2 -36 = 0 represents an ellipse in standard position. Find the coordinates of the foci and the equations of the directrices. The Foci are (+-f, 0) where f>0 I have worked out f=sqrt(5) not sure how to work …
9. ### Math

Write the equation of the ellipse using the given information: The ellipse has foci (4, 1) and (8, 1) and vertices (1, 1) and (11, 1);
10. ### Math

Write the equation of the ellipse using the given information: The ellipse has foci (–4, 0) and (–4, 4) and vertices (–4, –1) and (–4, 5);

More Similar Questions