Question

SOmeone check my answer please!

Answer 1

I think it is the last one?

Answer 2

if we can write it in the format:

y = x^2

we can check that against the 4ay=x^2 where a 0s the distance from the vertex to the focus and directix

Answer 3

or we can wolf it :) if speed is important

Answer 4

y = -5x^2+60x-176

y = -5(x^2 -12x) -176

y = -5(x^2 -12x +6^2) -176+5(6^2)

y = -5(x-6)^2 -176+ 180

y = -5(x-6)^2 + 14

as is; we know the vertex is at: (6,14) and it opens down since -5 is negative.

the directix will be above the vertex by comparison

Answer 5

Isn't -176+180 = 4?

Answer 6

good eye :) yes it is


y = -5(x-6)^2 + 4

(y-4) = -5(x-6)^2

(-1/5) (y-4) = (x-6)^2

we compare this to 4ay = x^2 we get:

4a = -1/5

a = -1/20

Answer 7

4 + 1/20 should be our dirextix; but id have to dbl chk it with the wolf to be sure

Answer 8

Thank you :) and so I did get the correct answer of 3 + 19/20 because 4- 1/20 = 3 and 19/20 right?

Answer 9

d = 81/20

Answer 10

a is an absolute value so we ignore the sign

Answer 11

"a" tells us how far from the vertex we go

Answer 12

the direction is going to be opposite of the open direction

Answer 13

y=4+|a| is the directix in this case

Answer 14

Really so when finding the c you use 1/4c and then, add that number to the (x, y + c) which is the focus, and then for the directrix its y = k - c?

Answer 15

id go with the second option

Answer 16

in your case I think you are used to: 4cy=x^2

where c is a measure of distance; not direction

Answer 17

direction indicates the focus or the directix; they are at polar ends of "c" from the vertex.

Focus is ini the direction of open; and Directix is in the direction of not the open

Answer 18

distance is an absolute value:

4-|c| = focus in this case

and 4 + |c| = directix

simply becasue the parabola opens downward

Answer 19

yep - i just wolfed it

Answer 20

i wolfed it afterwards to see where I mighta messed it up at :)

Answer 21

OH!! I get it now! haha thank you so much! If It weren't for you I would have got the answer wrong haha, thank you x 10,000

Answer 22

youre welcome, and good luck with it all :)

Answer 23

Thanks you :)