I will explain you and pair two of the equations as an example to you. Then, you must pair the others.
1) Two circles are concentric if they have the same center and different radii.
2) The equation of a circle with center xc, yc, and radius r is:
(x - xc)^2 + (y - yc)^2 = r^2.
So, if you have that equation you can inmediately tell the coordinates of the center and the radius of the circle.
3) You can transform the equations given in your picture to the form (x -xc)^2 + (y -yc)^2 = r2 by completing squares.
Example:
Equation: 3x^2 + 3y^2 + 12x - 6y - 21 = 0
rearrange: 3x^2 + 12x + 3y^2 - 6y = 21
extract common factor 3: 3 (x^2 + 4x) + 3(y^2 -2y) = 3*7
=> (x^2 + 4x) + (y^2 - 2y) = 7
complete squares: (x + 2)^2 - 4 + (y - 1)^2 - 1 = 7
=> (x + 2)^2 + (y - 1)^2 = 12 => center = (-2,1), r = √12.
equation: 4x^2 + 4y^2 + 16x - 8y - 308 = 0
rearrange: 4x^2 + 16x + 4y^2 - 8y = 308
common factor 4: 4 (x^2 + 4x) + 4(y^2 -8y) = 4*77
=> (x^2 + 4x) + (y^2 - 2y) = 77
complete squares: (x + 2)^2 - 4 + (y - 1)^2 - 1 = 77
=> (x + 2)^2 + (y - 1)^2 = 82 => center = (-2,1), r = √82
Therefore, you conclude that these two circumferences have the same center and differet r, so they are concentric.
Answer: 363.6 miles.
Step-by-step explanation:
1. You know that the motorist traveled 250 miles on 11 gallons of gas. Then, to calculate how far could the motorist go on 16 gallons of gas (with the same vehicle), you only need to multiply 16 gallons by 250 miles and divide this by 11 gallons.
2. Keeping this on mind, let's call the distance the motorist could go on 16 gallons of gas 
, then:
3. Therefore, you obtain the following result:
Answer:
C. -4 = 16x
Step-by-step explanation:
That is the graph i got when I typed -4 = 16x.
Brainliest Please!!!
- Hermionia
The slope is –3.
Solution:
<u>To find the slope of the line:</u>
The given points in the table lie on a line.
Take any two points from the line.
Let the points are (0, 2) and (3, –7).
Slope of the line formula:
m = –3
The slope is –3.
Each piece will be 26cm by 4cm.
Width is 26 cm.
Length is 36 cm. The problem states that the length is 10 cm longer than the width. Since width is 26 I just added 10 to arrive at 36 cm.
36 / 9 = 4 cm.
The width will still be 26 but the length is now 4 cm.
Area = length * width
Area = 4 * 26
Area = 104 cm
