Answer:
a=0
Step-by-step explanation:
x²-2x+y²-4y-4=0
(x²-2x+1)+(y²-4y+4)-9=0
(x-1)² + (y-2)² = 3²
Center: (1,2) radius: 3
(1,2) on line 2x-y+a=0
2*1 - 2 + a = 0
a = 0
Actually,I believe it is the rule of 72
72/4.5 = 16 years
Answer:
a. 
b. 
c. 
Step-by-step explanation:
a. The volume of water initially in the fish tank = 15 liters
The volume of brine added per minute = 5 liters per minute
The rate at which the mixture is drained = 5 liters per minute
The amount of salt in the fish tank after t minutes = x
Where the volume of water with x grams of salt = 15 liters
dx = (5·c - 5·c/3)×dt = 20/3·c = 

b. The amount of salt, x after t minutes is given by the relation




c. Given that in 10 minutes, the amount of salt in the tank = 25 grams, and the volume is 15 liters, we have;




Step-by-step explanation:
We know that
Radius = Diameter/2
=> Radius = 2/2
=> Radius = 1 in
Now,
Volume of cylinder = πr²h
=> π × (1)² × 9
=> 9π in³
Since it is filled ⅔ of the volume
So,
Water to be putted = ⅔ × 9π = 6π in³
Answer:
D
Step-by-step explanation:
Passes through the x-axis at r and k