9 less than twice a number is 13. What is the number?
2 answers:
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Answer:
Step-by-step explanation:
The formula for a circle of radius r centered at (h, k) is ...
(x -h)^2 +(y -k)^2 = r^2
Both of the given points are on the line y=-1. The distance between them is the difference of their x-coordinates, 2 -(-2) = 4. So, the radius of the circle is 4 and the equation becomes ...
(x -2)^2 +(y -(-1))^2 = 4^2
(x -2)^2 +(y +1)^2 = 16 . . . . . . . . . matches choice A
