Parabolas have equations of the form ax^2 + bx + c = y where a is not equal to 0.
Determine the direction that this parabola opens:
y = 5x^2 + 10x - 5
A) up
B) down

Question

Parabolas have equations of the form ax^2 + bx + c = y where a is not equal to 0.
Determine the direction that this parabola opens:
y = 5x^2 + 10x - 5
A) up
B) down

phi · Answer

do you know the shape of a parabola? Can you sketch one ?

anonymous · Answer

No I do not know the shape, unless it's like this...

|dw:1396274468045:dw|

phi · Answer

yes, that is what it looks like.  However, it would be a frown
|dw:1396274605565:dw|

phi · Answer

*could be  (not would be)

phi · Answer

to figure out what you have, notice that in your picture,  as x gets bigger, the "y" value of your parabola gets bigger.
|dw:1396274671357:dw|

if you put in x=0 into your equation
y = 5x^2 + 10x - 5
you get
y = 5*0*0 +10 * 0 - 5
which simplifies to -5

now make x bigger.  If you have a "smile" parabola, the y will get bigger.  If you have a frown the y will get smaller (go down)