After modelling the mathematical statement and solving its equivalent mathematical relation, we get x = -36.
<h3>What is Equation Modelling?</h3>
Equation modelling is the process of writing a given mathematical statement in the form of a numeric mathematical expression taking into considerations the operations, constants and other variables.
Given in the question is a number such that twice the difference of a number and 9 is equal to three times the sum of the number and 6.
Assume that the number is x. Now, we will model the equation and solve for x. According to the question, the following mathematical relation represents the statement-
2(x - 9) = 3(x + 6)
2x - 18 = 3x + 18
x = - 36
Therefore, the number is -36.
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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:
- .
- -2
- -5
- 20
- -12
Step-by-step explanation:
hope it helps
A. 2/5 B. 1/3 just like the other person said lol
Answer:
Time spent rowing down stream 
Speed of boat in still water 
Step-by-step explanation:
Let speed of boat in still water be 
Speed of current 
Speed of boat down stream = 
Distance rowed down stream = 2400 m
Time spent rowing down stream = 
=
Speed of boat up stream = 
Distance rowed up stream = 
Time spent rowing up stream = 
We know that,
So,
Cross multiplying
Dividing both sides by 
Adding 60 to both sides.
Subtracting both sides by 
Dividing both sides by 5.
∴ 
Speed of boat in still water 
Time spent rowing down stream =
