The answer is (x+4)² + y² = 16
x² + y² - 8x = 0
[reorder the terms]
x² - 8x + y² = 0
[to complete the square, add 16 to both sides]
x² - 8x + 16 + y² = 16
[write the expression as a product and 16 as an exponent]
x² - 2 × x × 4 + 4² + y² = 16
[using a² + 2ab + b² = (a + b)², factor the expression]
(x + 4)² + y² = 16
Since this equation can be written as
(x + p)² + (y - q)² = r², it represents a circle.
