Answer:

Step-by-step explanation:
The general equation of a circle is as follows:

In which the center is
, and r is the radius.
In this problem, we have that:

So

Passing through (2,-4)
We replace into the equation to find the radius.



The equation of the circle is:

Answer:
5y+5
Step-by-step explanation:
distribute the 1/2
(5y+2)+3
(add the 3- it can't be added to 5y because they aren't like terms)
5y+5
Answer:
(C)4
Step-by-step explanation:
Given the line: 
The gradient of the line, 
A line perpendicular to the given line will have a gradient,
(by definition of perpendicularity).
Therefore, a perpendicular line that passes through the point (4,1) is:

Comparing with the slope-intercept form y=mx+x, the slope of the perpendicular line, b=4.