Answer:
C
Step-by-step explanation:
The equation of a circle in standard form is
(x - h)² + (y - k)² = r²
where (h, k)are the coordinates of the centre and r is the radius
Given
2x² + 2y² - 4x + 16y = 128 ( divide through by 2 )
x² + y² - 2x + 8y = 64 ( collect x and y terms together )
x² - 2x + y² + 8y = 64
Using the method of completing the square
add ( half the coefficient of the x/ y terms )² to both sides
x² + 2(- 1)x + 1 + y² + 2(4)y + 16 = 64 + 1 + 16
(x - 1)² + (y + 4)² = 81 ← in standard form
with centre = (h, k ) = (1, - 4 ) → C
