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Define a differential equation.

An equation that relates a function with its derivatives.

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Define a differential equation.

An equation that relates a function with its derivatives.

What does dydt\frac{dy}{dt} represent in exponential models?

The rate of change of a quantity yy with respect to time tt.

What does the constant kk represent in the differential equation dydt=ky\frac{dy}{dt} = ky?

The rate constant, indicating the rate of growth (if k>0k > 0) or decay (if k<0k < 0).

Define y0y_0 in the context of exponential models.

The initial value of the quantity yy at time t=0t = 0.

What is an exponential model?

A mathematical model that describes the growth or decay of a quantity over time, where the rate of change is proportional to the current amount.

What is the meaning of 'e' in exponential models?

Euler's number, the base of the natural logarithm, approximately equal to 2.71828; important in continuous growth/decay situations.

Define 'rate of change' in calculus.

The measure of how a quantity is changing with respect to another quantity, typically time; represented by a derivative.

What is meant by 'proportional to' in the context of exponential growth?

The rate of growth is a constant multiple of the current value.

Define 'initial condition' in a differential equation.

The value of the function at a specific point, often at t=0t=0, used to find a particular solution.

What is meant by 'separating variables' in solving differential equations?

A technique where terms involving one variable are isolated on one side of the equation, and terms involving the other variable are on the other side, allowing for integration.

What is the general solution to the differential equation dydt=ky\frac{dy}{dt} = ky?

y=y0ekty = y_0 e^{kt}

Formula to find kk given y(t)y(t), y0y_0, and tt?

k=1tln(y(t)y0)k = \frac{1}{t} \ln(\frac{y(t)}{y_0})

What is the integral of 1ydy\frac{1}{y} dy?

lny+C\ln|y| + C

How to calculate the population at time t?

y=y0cdotekty = y_0 cdot e^{kt}

How do you find the constant kk in the exponential growth model?

Using the formula k=ln(yy0)tk = \frac{\ln(\frac{y}{y_0})}{t}, where yy is the population at time tt, and y0y_0 is the initial population.

What is the formula for the amount of a drug remaining in the bloodstream after time tt?

A(t)=A0ektA(t) = A_0 e^{kt}, where A0A_0 is the initial amount and kk is the decay constant.

Formula for the rate of change?

dydt\frac{dy}{dt}

What is the formula for the exponential model when the rate is proportional to the current size?

dydt=ky\frac{dy}{dt} = ky

What is the formula to solve for yy when given lny=kt+Cln|y| = kt + C?

y=ekt+C=eCekty = e^{kt+C} = e^C e^{kt}

What is the formula to determine the constant C?

eC=y0e^C = |y_0|

How to solve for kk when given the initial value and a value at time tt?

  1. Substitute the given values into y=y0ekty = y_0 e^{kt}. 2. Divide both sides by y0y_0. 3. Take the natural logarithm of both sides. 4. Solve for kk.

Steps to model population growth given initial population and growth rate?

  1. Write the equation y=y0ekty = y_0 e^{kt}. 2. Determine y0y_0 (initial population). 3. Find kk (growth rate). 4. Substitute y0y_0 and kk into the equation.

Steps to predict future population using exponential model?

  1. Determine the exponential model y=y0ekty = y_0 e^{kt}. 2. Substitute the known values of y0y_0, kk, and tt (future time). 3. Calculate yy to find the future population.

How do you solve an exponential decay problem?

  1. Identify the initial amount y0y_0. 2. Use the given information to find the decay constant kk. 3. Substitute y0y_0 and kk into the equation y=y0ekty = y_0 e^{kt}. 4. Solve for the desired variable.

Steps to solve for time tt when given the initial and final values?

  1. Substitute the given values into y=y0ekty = y_0 e^{kt}. 2. Divide both sides by y0y_0. 3. Take the natural logarithm of both sides. 4. Solve for tt using t=ln(yy0)kt = \frac{\ln(\frac{y}{y_0})}{k}.

How to find the decay constant kk in a radioactive decay problem?

  1. Use the half-life formula k=ln(2)Tk = \frac{\ln(2)}{T}, where TT is the half-life. 2. Substitute the given half-life value into the formula. 3. Calculate kk.

How to solve for the initial population when given the population at time tt?

  1. Substitute the given values into y=y0ekty = y_0 e^{kt}. 2. Solve for y0y_0 using y0=yekty_0 = \frac{y}{e^{kt}}.

Steps to find the time it takes for a population to double?

  1. Set y=2y0y = 2y_0 in the equation y=y0ekty = y_0 e^{kt}. 2. Simplify to 2=ekt2 = e^{kt}. 3. Take the natural logarithm of both sides. 4. Solve for tt using t=ln(2)kt = \frac{\ln(2)}{k}.

How to determine the equation for the amount of drug remaining?

  1. Identify the initial amount A0A_0. 2. Use the given information to find the constant kk. 3. Write the equation A(t)=A0ektA(t) = A_0 e^{kt}.

How to solve a problem where bacteria doubles in five hours?

  1. Assign an initial value to the bacteria, y0y_0. 2. Note that after 5 hours, y=2y0y = 2y_0. 3. Use the exponential growth equation to find kk. 4. Use the exponential growth equation to find tt when y=4y0y = 4y_0.