Answer
Find out the which coordinate pair identifies the center of the circle represented by 4x² + 4y² − 16x − 24y + 36 = 0.
To prove
The general equation of the circle is
(x - h)² + (y - k)² = r²
Where h,k are the centre and r is the radius.
4x² + 4y² − 16x − 24y + 36 = 0
Divided both side by 4.
x² + y² − 4x − 6y + 9= 0
Add and subtract 4 and 9
x² + y² − 4x − 6y + 4 -4 +9 - 9 +9= 0
x² + y² − 4x − 6y + 4 -4 + 9 - 9 +9= 0
x² + 4 - 2× 2 × x + y² + 9 - 2 × 3 × y = 9 + 4 - 9
using the formula ( a + b )² = a² + b² +2ab
(x - 2)² + (y - 3)² = 2²
Compare this with the general equation of circle.
Thus
h = 2 , k = 3
Option A is correct .
I think the answer is 6. ABC, ACB, BAC, BCA, CAB, and CBA.
