Deriving and using the equation of a circle

In the equation (x - 3)² + (y + 4)² = 121, the radius of the circle is

• 242

• 11

• 121

• 22

Which is the correct equation of a circle whose centered at (-1, -5) and has a radius of 5?

• (x + 1)² + (y - 5)² = 25

• (x - 1)² + (y - 5)² = 25

• (x - 1)² + (y + 5)² = 25

• (x + 1)² + (y + 5)² = 25

In the equation (x-3)²+(y+4)²=121, the center of the circle is at...

• (3, -4)
• (-3, 4)
• (4, 3)
• (-4, -3)

A circle is represented by the equation  x²+y²+4x+6y-36=0? . Which of the following shows the location of the center of the circle?

• center (2, 3)

• center (-2, -3)

• center (4, 6)

• center (-4, -6)

Given the equation of a circle $x^2+y^2-10x+16y-30=0$ 
Check all of the statements that are true.

•  $\left(x-5\right)^2+\left(y+8\right)^{2\ }=119$  

• Center is (5, -8)  Radius= 10.9

• Center is (-5, 8)  Radius is = 10.9

•  $\left(x+5\right)^2+\left(y-8\right)^2=119$  

What is the equation of the circle?

• $x^2+y^2+2x+2y-1=0$

• $x^2+y^2+2x-2y-1=0$

• $x^2+y^2+2x+2y-7=0$

• $x^2+y^2-2x-2y-7=0$

Plot the circle given by the equation (x+4)^2 + (y-5)^2 = 25 on a coordinate plane

• The circle should be plotted with center at (0, 0) and radius 5.

• The circle should be plotted with center at (3, -2) and radius 7.

• The circle should be plotted with center at (-5, 4) and radius 6.

• The circle should be plotted with center at (-4, 5) and radius 5.

Select the matching graph.

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Identify the description that matches this equation.  $x^2+y^2=49$  

• a circle with center (0, 0) and radius 7

• a circle with center (1, 1) and radius 7

• a circle with center (0, 0) and radius 49

• a circle with center (0, 0) and radius 1