Write an equationin standard form for the ellipse with foci (7, 0) and (-7, 0) and y-intercepts 6 and -6.
a. x^2/36 + y^2/85 = 7
b. x^2/36 + y^2/85 = 1
c. x^2/85 + y^2/36 = 7
d. x^2/36 + y^2/36 = 1

Question

Write an equationin standard form for the ellipse with foci (7, 0) and (-7, 0) and y-intercepts 6 and -6.  
a. x^2/36 + y^2/85 = 7  
b. x^2/36 + y^2/85 = 1  
c. x^2/85 + y^2/36 = 7  
d. x^2/36  +  y^2/36 = 1

mertsj · Answer

$$c ^{2}=a ^{2}-b ^{2}$$

mertsj · Answer

49=a^2-36
a^2=85
Should be x^2/85+y^2/36=1

mertsj · Answer

Did you type an answer wrong?

mertsj · Answer

c=7, b = 6

anonymous · Answer

no, those answer choices are correct.

mertsj · Answer

c should say = 1

mertsj · Answer

Does it say = 1?

anonymous · Answer

no, c says =7

mertsj · Answer

Something has to be wrong.  The foci are on the x axis which means the major axis is horizontal and (a,0) and (-a,0) are the endpoints of the major axis.  The y intercepts are (0,6) and (0,-6) which means that b = 6.

mertsj · Answer

So a^2 must be 85.  The standard form of an ellipse with major axis horizontal and center at origin is x^2/a^2 +y^2/b^2 =1

mertsj · Answer

So x^2/85 +y^2/36 = 1 is the correct equation.

anonymous · Answer

Maybe the person that wrote it, wrote it wrong. but I do understand what you mean.