If e and e¹ be the eccentricities of two conics $\mathrm{s}=0$ and ${\mathrm{s}}^1=0$ and if ${\mathrm{e}}^2+{\mathrm{e}}^{1^2}=3$ then 

For a parabola the eccentricity is 1.

So,$e^2+e{\text{'}}^2=1+1=2$=1+1=2
For an ellipse the eccentricity is less than 1
∴ For a hyperbola the eccentricity is greater than 1. So, the conics can be hyperbolas