The radius of the circle x² + y² + 2x + 4y + 1 = 0 is
Question 1
Q1. The radius of the circle x² + y² + 2x + 4y + 1 = 0 is
Answer: 2
Explanation: The radius is given by √(g² + f² - c), where g = 1, f = 2, and c = 1, so √(1 + 4 - 1) = √4 = 2.