The Ellipse (x^2/9)+(y^2/16)=1 is _________

A) A vertical ellipse with foci at (0, +-sqroot7)

B) A horizontal ellipse with foci at (+-sqroot7, 0)

C) An ellipse with a minor axis of length 8

D) An ellipse with a major axis of length 6

thanks

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- Jul 4th 2007, 09:32 AMandy11Help with Ellipse Problem
The Ellipse (x^2/9)+(y^2/16)=1 is _________

A) A vertical ellipse with foci at (0, +-sqroot7)

B) A horizontal ellipse with foci at (+-sqroot7, 0)

C) An ellipse with a minor axis of length 8

D) An ellipse with a major axis of length 6

thanks - Jul 4th 2007, 10:05 AMSoroban
Hello, Andy!

We can "eyeball" the equation . . .

Quote:

The ellipse . $\displaystyle \frac{x^2}{9}+ \frac{y^2}{16} \:=\:1$ .is:

(A) A vertical ellipse with foci at $\displaystyle (0,\,\pm\sqrt{7})$

(B) A horizontal ellipse with foci at $\displaystyle (\pm\sqrt{7},\,0)$

(C) An ellipse with a minor axis of length 8

(D) An ellipse with a major axis of length 6

We see that the major (longer) axis is in the y-direction, a "vertical" ellipse.

. . The length of the major axis is 8; the minor axis has length 6.

This eliminates answer-choices $\displaystyle (B),\,(C),\,(D)$

- Jul 4th 2007, 10:07 AMandy11
thanks