The rate at which a radioactive substance decay is proportional to the amount A(t) of the substance remaining at time t. At initial time of observation, the mass of this substance is 10g. Formulate the Initial-Value-Problem (IVP) for the amount A(t).

Respuesta :

Answer:

[tex]A (t)=10e^{kt}[/tex]

Step-by-step explanation:

[tex]\frac{dA}{dt}\propto A(t)[/tex]

[tex]\frac{dA}{dt}=kA(t), where k=decay constant[/tex]

[tex]\frac{dA}{A}=k dt[/tex]

Taking the integral of both sides

[tex]\int{\frac{dA}{A}}=\int k dt[/tex]

[tex]ln A =kt+C\\[/tex], where C=constant of integration.

Taking the exponents of both sides

[tex]e^{ln A} =e^{kt+C}=e^{kt}Xe^{C}\\[/tex]

Since the exponential of a constant is still a constant

[tex]A (t)=Ce^{kt}[/tex]

At t=0, A(t)=10 g

[tex]10=C[/tex]

Therefore the initial value problem is given as:

[tex]A (t)=10e^{kt}[/tex]