Help with Classifying Conics by Using the Discriminant

Question

darkbluechocobo · Answer

Identify the value for C in the following equation that would make the conic section a hyperbola: 2x2 + Cy2 + 3x + 5y + 1 = 0

darkbluechocobo · Answer

0^2 -4(2)(c)>0
-8c>0

darkbluechocobo · Answer

@perl This looks strange, Did I do something wrong?

michele_laino · Answer

we have to solve this equation:
$$0 - 4 \times 2 \times C > 0$$

darkbluechocobo · Answer

Yes, but I am confused. -4x8=-8*c>0
you divide -8 by both sides and you get c>0/-8
and that doesn't match with what the multiple choice I have does s:

rational · Answer

hey

michele_laino · Answer

we get:
C<0
so all negative values for C gives an hyperbola

michele_laino · Answer

give*

rational · Answer

just a side note, there was no "xy" term in the given equation
that means no rotation
so it will be a hyperbola if the coefficeints of quadratic terms have opposite signs

darkbluechocobo · Answer

C = 1
	
C = 2
	
C = 3/5 
	
C = 5
	
C = -1

Should i just take a gander with the questions?

michele_laino · Answer

it is very simple, you have to pick the last option