Find the centre and radius of the circles 2x² + 2y² – x = 0.

7

Find the centre and radius of the circles x² + y² – 4x – 8y – 45 = 0.

8

Find the centre and radius of the circles x² + y² – 8x + 10y – 12 = 0.

10

Find the equation of the circle passing through the points (4,1) and (6,5) and
whose centre is on the line 4x + y = 16.

11

Find the equation of the circle passing through the points (2, 3) and (–1,1) and
whose centre is on the line x – 3y – 11 = 0.