Question

The equation of a circle is (x - 4)2 + (y + 1)2 = 9. Which graph best represents the circle?

Answer 1

i dont understand how to do this at all could you tell me what the answer is and explain it too?

Answer 2

The question gives you an equation which is a circle in standard form. That makes this problem very simple. Reversing the signs in the parentheses and taking those constants will give you the center point of the circle.

To explain further, "x-4" means the center x coordinate must be +4. The same goes for the "y+1"...reverse the sign of the +1 to get a center y coordinate of -1.

So which image shows a circle with a center of (4,-1)?

Answer 3

You know that (y+1) means the graph is shifted up by 1,... ok, I was too late :)

Answer 4

The one that has the center would be A?

Answer 5

and thanks @jkristia

Answer 6

Yes. If you like, you can verify the answer by solving the equation for y and graphing the result.

Answer 7

ok i will just take the yes lol thanks :)

Answer 8

@jkristia: (y+1) means it's actually shifted down by 1 :)

Answer 9

oops - I got it wrong..

Answer 10

yes - correct

Answer 11

It's counter-intuitive but the signs have to be reversed to see what the graph is doing

Answer 12

lol thanks for trying anyways @jkristia

Answer 13

and thanks @Shane_B

Answer 14

you're very welcome :)