fish tank initially contains 35 liters of pure water. Brine of constant, but unknown, concentration of salt is flowing in at 5 liters per minute. The solution is mixed well and drained at 5 liters per minute. Let xx be the amount of salt, in grams, in the fish tank after tt minutes have elapsed. Find a formula for the rate of change in the amount of salt, dx/dtdx/dt, in terms of the amount of salt in the solution

Respuesta :

Answer:

Therefore, the rate of change in the amount of salt is [tex]\frac{dx}{dt} =( 5c}{ - \frac{x }{20})[/tex]

[tex]\frac{grams }{min}[/tex]

Explanation:

Given:

Initial volume of water [tex]V = 35[/tex] lit

Flowing rate = 5 [tex]\frac{Lit}{min}[/tex]

The rate of change in the amount of salt is given by,

   [tex]\frac{dx}{dt} =[/tex] ( Rate of salt enters tank - rate of sat leaves tank )

Since tank is initially filled with water so we write that,

[tex]x(0) = 0[/tex]

Let amount of salt in the solution is [tex]c[/tex],

  [tex]\frac{dx}{dt} = \frac{5c}{1 } - \frac{x(t) \times 5}{100}[/tex]

  [tex]\frac{dx}{dt} =( 5c}{ - \frac{x }{20})[/tex] [tex]\frac{grams}{min}[/tex]

Therefore, the rate of change in the amount of salt is [tex]\frac{dx}{dt} =( 5c}{ - \frac{x }{20})[/tex]

[tex]\frac{grams }{min}[/tex]