Well first I'd like to say that I'm happy to meet you all! My friends told me you guys here are some of the smartest there is so I've decided to ask for some help here!

Here's my 1st question:

The typical planetary orbit can be modeled by an ellipse with the start at one focucs.

Suppose that two planets revolve around the same star.

How many possible points of intersection could there be?

a)0 or 1

b)0,1,or 2

c)0,1,2,or 4

d)0,1,2,3,or 4

I think its A. What do you guys say?

2nd question

Solve by using elimination:

4x^{2}+9y^{2}=36

4x^{2}-25y^{2}=100

a) (3,0) (-3,0)

b) no solution

c) (0, 32/17) (0,-32/17)

d) (3,32/17) (3,-32/17), (-3,32/17) , (-3,-32/17)

I said it was b. Thoughts?

Lastly:

Solve by using elimination or substitution:

x^{2}+4y^{2}=7

2y^{2}-x=4

a) (-1,√6/2)

b) (0,√2), (0,-√2)

c) (1,±√10/2)

d) (-1,√6/2) (-1, -√6/2)

I said it c. Thoughts?

My test is tomorrow morning so if anyone could help me? I'd be more than thankful! Thanks.

PS: ± = plus or minus

√ = square root.... so √10/2 means the square root of 10 over 2.