Write an equation in standard form for the circle.

Question

anonymous · Answer

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anonymous · Answer

If you could provide coordinates that would be incredibly helpful.
However, a general equation for circles is$$(x-h)+(y-k)=r ^{2}$$

Where h is the X coordinate of the center, K is the Y coordinate of the center, and R is the radius.

anonymous · Answer

i don't know the coordinates but i know the choices on my practice sheet are:
(x – 3)2 + (y + 5)2 = 64
(x + 3)2 + (y + 5)2 = 64
(x – 3)2 + (y – 5)2 = 64
(x + 3)2 + (y – 5)2 = 64

anonymous · Answer

Well, since your circle appears to have a center in the first quardrant, I would hazzard a guess and say any expression with a positive factor is out the window.  So A, B, and D are all out, that leaves C.

anonymous · Answer

oh okay thank you so much :)

anonymous · Answer

do you think you can help me with one more?

anonymous · Answer

That's what we're on here for! Of course.

anonymous · Answer

okay i will post another one

anonymous · Answer

Write an equation for the translation of x2 + y2 = 49 by 3 units left and 4 units up

anonymous · Answer

When your x term has a positive factor, it moves your graph to the left.  When your x tertm has a negative factor, it moves your graph to the right. And similarly for the y term.  I just gave you a way to find the answer to your next question.

anonymous · Answer

but the choices don't show graphs they show a equation

anonymous · Answer

You don't need a graph.  When your graph gets moved to the left a units, you replace x with x+a, and when your graph gets moved to the right a units, you replace x with x-a.  Similarly for when the graph gets moved up and down.    So, with that information, can you answer your next question.

anonymous · Answer

I don't want to just give you the answer, I want you to understand how to get the answer on your own.

anonymous · Answer

To use that in an example, if your center is at -2, 5 your equation is (x+4) + (y-5).

If a coordinate is negative, its respective term would be (x+h) or (y+k) depending on which coordinate (see my above answer for what h or k mean.

anonymous · Answer

oh okay you then would the answer be (x + 3)^2 + (y + 4)^2 = 49

anonymous · Answer

The answer would have (y-4) and not (+4) as it moved up, not down.

Remember, the equation is negative (when the coordinate is positive).

anonymous · Answer

ohhh okay i mixed that part up so then this is my answer (x + 3)^2 + (y – 4)^2 = 49

anonymous · Answer

Yes, that is correct.

anonymous · Answer

okay thank youu