SOLUTION: find the ellipse in standard form that passes through the point(3,sqrt(7)) and (sqrt(3),3)?

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Question 480300: find the ellipse in standard form that passes through the
point(3,sqrt(7)) and (sqrt(3),3)?

Found 2 solutions by Edwin McCravy, Alan3354:
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
point(3,sqrt%287%29) and (sqrt%283%29,3)?


Here are those two points plotted: approximately (3,2.6) and (1.7,3)



I will assume you meant the ellipse with center at the origin; 
otherwise there would be many possibilities.

Since those points are as they are, the major axis will be
horizontal and the ellipse will look like this:  ᆼ
So its equation will be:

x%5E2%2Fa%5E2%2By%5E2%2Fb%5E2=1

Substitute the first point: (x, y) = (3, sqrt%287%29)


%283%29%5E2%2Fa%5E2%2B%28sqrt%287%29%29%5E2%2Fb%5E2=1
9%2Fa%5E2%2B7%2Fb%5E2=1

Substitute the second point: (x, y) = (sqrt%283%29,3)?

%28sqrt%283%29%29%5E2%2Fa%5E2%2B%283%29%5E2%2Fb%5E2=1
3%2Fa%5E2%2B9%2Fb%5E2=1

We have this system of equations:

system%289%2Fa%5E2%2B7%2Fb%5E2=1%2C3%2Fa%5E2%2B9%2Fb%5E2=1%29

Important!:
DO NOT CLEAR OF FRACTIONS BUT SOLVE BY ELIMINATION:

Multiply the 2nd equation through by -3 to eliminate the
terms in aČ:

system%289%2Fa%5E2%2B7%2Fb%5E2=1%2C-9%2Fa%5E2-27%2Fb%5E2=-3%29

Add the equations:

-20%2Fb%5E2=-2

-20=-2b%5E2

10=b%5E2

Substitute 10 for bČ in the first equation:

9%2Fa%5E2%2B7%2Fb%5E2=1

9%2Fa%5E2%2B7%2F10=1

Multiply through by 10aČ

90%2B7a%5E2=10a%5E2

90=3a%5E2

30=a%5E2

Substitute 30 for aČ and 10 for bČ

x%5E2%2Fa%5E2%2By%5E2%2Fb%5E2=1


x%5E2%2F30%2By%5E2%2F10=1

That's the equation.  

The vertices are (±sqrt%2830%29,0), approximately (±5.5,0)
The covertices are (0,±sqrt%2810%29), approximately (0,±3.2)
Here's the graph:




Edwin



Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
2 points don't define an ellipse.
An infinite # of ellipses pass thru those 2 points.