Question:medium

A bacteria sample of certain number of bacteria is observed to grow exponentially in a given amount of time. Using exponential growth model, the rate of growth of this sample of bacteria is calculated.


The differential equation representing the growth of bacteria is given as: \[ \frac{dP}{dt} = kP, \] where \( P \) is the population of bacteria at any time \( t \). bf{Based on the above information, answer the following questions:
[(i)] Obtain the general solution of the given differential equation and express it as an exponential function of \( t \). 
[(ii)] If the population of bacteria is 1000 at \( t = 0 \), and 2000 at \( t = 1 \), find the value of \( k \).

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For exponential growth or decay, always separate variables, integrate, and rewrite in exponential form.
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Solution and Explanation

(i) General Solution of the Differential Equation: The provided differential equation is: \[ \frac{dP}{dt} = kP. \] Variable separation yields: \[ \frac{1}{P} \, dP = k \, dt. \] Integrating both sides: \[ \int \frac{1}{P} \, dP = \int k \, dt. \] The integration results in: \[ \ln |P| = kt + C, \] where \( C \) is the constant of integration. Expressing this in exponential form: \[ P = e^{kt + C} = e^C \cdot e^{kt}. \] Setting \( e^C = P_0 \), representing the initial population: \[ P = P_0 e^{kt}. \] Final Answer (i): The general solution is: \[ P = P_0 e^{kt}. \]
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