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.
Let's find the equivalent expressions ~
#1. PROBLEM
#2. PROBLEM
This intersection means that u have to find the same number in both sets
the answer is 3 , 7 , 13
i am a mathematics teacher. if anything to ask please pm me
Answer:
5. independent variable hours (h); dependent variable; total cost
6. t= 10h + $4.50
Step-by-step explanation:
The final result in dependent on how many hours he uses the boat.
Problem 1
subtract 3 x
5y=-3x+11
divide 5
y=3/5x+2.2'
Problem 2
add 5x
7y=5x+9
divide 7
y=5/7x+1.3'
'notice'
you can put 2.2 into a fraction (11/5) and 1.3 (9/7) if your teacher allows it, but i put them into decimals
