Let y(t) represent the level of water in inches at time t in hours. Then we are given ...
y'(t) = k√(y(t)) . . . . for some proportionality constant k
y(0) = 30
y(1) = 29
We observe that a function of the form
y(t) = a(t - b)²
will have a derivative that is proportional to y:
y'(t) = 2a(t -b)
We can find the constants "a" and "b" from the given boundary conditions.
At t=0
30 = a(0 -b)²
a = 30/b²
At t=1
29 = a(1 - b)² . . . . . . . . . substitute for t
29 = 30(1 - b)²/b² . . . . . substitute for a
29/30 = (1/b -1)² . . . . . . divide by 30
1 -√(29/30) = 1/b . . . . . . square root, then add 1 (positive root yields extraneous solution)
b = 30 +√870 . . . . . . . . simplify
The value of b is the time it takes for the height of water in the tank to become 0. It is 30+√870 hours ≈ 59 hours 29 minutes 45 seconds
Answer:
The answer to your question is:
x₁ = 0
x₂ = -3
x₃ = 3
Step-by-step explanation:
Equation 4x³ = 36 x
Process
4x³ - 36x = 0
4x (x² - 9) = 0
4x (x + 3)(x - 3) = 0
Finally
4x = 0 x + 3 = 0 x -3 = 0
x = 0/4 x₂ = -3 x₃ = 3
x₁ = 0
I agree with the other person ^^^
Nonmembers: $10 per hour = 10h
Members: $300 and $4 per hour = 300 + 4h
10h > 300 + 4h
6h > 300
h > 50
You'd need to use it for more than 50 hours.