Question

I need help answering the question in the picture provided

Answer 1

(a).

Equation of circle is x² + y² - 25 = 0

(b).

(-5, 0) » yes

(√7, 1) » no

(-3, √21) » no

(0, 7) » no

Explanation:

(a).

If centred at origin, centre is (0, 0)

General equation of circle:

`{ \boxed{ \bf{ {x}^(2) + {y}^(2) + 2gx + 2fy + c = 0}}}`

but g and f are 0:

`{x}^(2) + {y}^(2) + c = 0 \\ but : \\ c = {g}^(2) + {f}^(2) - {r}^(2) \\ c = { - 25}`