Write the standard equation of a circle with center (−1, −1) and radius 1.

Formula for circle:
(x - h)^2 + (y - k)^2 = r^2
Where (h, k) is the cry and r is the radius.
(x - - 1)^2 + (y - - 1)^2 = 1^2
(x + 1)^2 + (y + 1)^2 = 1

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.