Question

What is the standard form of equation of a circle with center at (-2, -3) and passing through the point (-2, 0)?

A. (x + 2)2 + (y + 3)2 = 9
B. (x − 2)2 + (y − 3)2 = 16
C. (x − 2)2 + (y − 3)2 = 4
D. (x + 2)2 + (y + 3)2 = 16
E. (x − 2)2 + (y + 3)2 = 9

Answer 1

general form is

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

where (a,b) is the center and r = radius.

Answer 2

so if you replace a with -2 and y with -3 and simplify you'll be able to see which ones of the choices it could be.

Answer 3

(x - (-2))^2 + (y - (-3))^2 = r^2


what does -(-2) and -(-3) simplify to?

Answer 4

- 2 negatives together like this make a plus

Answer 5

so ( x --2) = (x + 2)

Answer 6

do you follow what I mean?

Answer 7

dont worry about the r^2 at the moment
can you work out what the left part of the equation will be?

Answer 8

r u there?

Answer 9

You kinda helped but I don't really think you understand it. But I understand it alil better now so thank you @welshfella

Answer 10

Oh i understand it alright.
from the above reasoning you'll find its 1 of 2 choices.
Then to find the correct choice you can plug in the point (-2 ,0) - that is x = -2 and y = 0
and see which one fits

Answer 11

yw

Answer 12

can you see what left side of the equation will be
it will start with
(x + 2)^2