The curve must have this orientation, since we know it has horizontal axis and passes through `(2, -1)`:
So we need to use the general formula
We need to find `p`. We know the curve goes through `(2, -1)`, so we substitute:
`(-1)^2= 4(p)(2) `
→ `1 = 8p`
→ `p = 1/8`.
So the required equation is `y^2=x/2`.