Question

Please and thank you!
The correct answer is: B
Can anyone show me how to do it :)
What is the equation of the circle with radius 9 and center (–2, 3)?
A x2 + y2 – 4x + 6y + 4 = 0
B x2 + y2 + 4x – 6y – 68 = 0
C x2 + y2 + 6x – 4y + 4 = 0
D x2 + y2 – 6x + 4y – 68 = 0

Answer 1

use standard form
(x-a)^2 + (y-b)^2 = r^2

where (a,b) is center and r = radius of the circle
plug in your values and expand ing will give you B

Answer 2

So what you have to do here is complete the square for both the x and y parts of the equation to get it in the form:

(x-a)^2+(y-b)^2=c^2

Answer 3

and how do u get 68

Answer 4

when you actually expand it out
you will have 4+9-81(ignoring all the variables)

Answer 5

i never got -81

Answer 6

(x + 2)^2 + (y -3)^2 = 81
right?

Answer 7

ohh whoops i forgot to square 9 thanks

Answer 8

giving 81 -4 - 9 = 68