All Flashcards
What is an exponential function?
A function of the form , where a is the initial value, b is the base (b > 0, b ≠ 1), and x is the exponent.
Define exponential growth.
Exponential growth occurs when the base . The function increases rapidly as x increases.
Define exponential decay.
Exponential decay occurs when . The function decreases rapidly as x increases.
What is the initial value in ?
The initial value is 'a', which represents the y-intercept of the function.
What is the domain of an exponential function?
The domain of an exponential function is all real numbers, .
What is a vertical shift?
A transformation of the form , which shifts the graph of vertically by k units.
What does concavity mean for exponential functions?
Concavity describes the curvature of the graph. Exponential functions are either always concave up or always concave down.
Define extrema in the context of exponential functions.
Extrema are maximum or minimum values of a function. Exponential functions do not have extrema on an open interval.
What is the base 'b' in exponential functions?
The base 'b' is a positive number not equal to 1 that determines whether the function represents growth or decay.
What is the significance of 'a' in ?
'a' represents the initial amount or starting value of the exponential function at x = 0.
Explain how the base 'b' affects the behavior of an exponential function.
If b > 1, the function represents exponential growth, increasing rapidly. If 0 < b < 1, the function represents exponential decay, decreasing rapidly.
Describe the impact of a vertical shift on an exponential function's graph.
A vertical shift moves the entire graph up or down. Adding a constant 'k' shifts the graph up if k > 0 and down if k < 0.
Explain the concept of limits in the context of exponential functions.
Limits describe the behavior of the function as x approaches infinity or negative infinity. Growth functions tend to infinity, while decay functions tend to zero as x approaches infinity.
Why do exponential functions not have inflection points?
Exponential functions are always either concave up (growth) or concave down (decay), so their concavity never changes, meaning no inflection points.
Explain why exponential functions do not have extrema on open intervals.
Exponential functions are always increasing or always decreasing; therefore, they do not have maximum or minimum values on an open interval.
How do exponential functions model real-world phenomena?
Exponential functions are used to model situations with rapid growth or decay, such as population growth, compound interest, and radioactive decay.
Describe the relationship between the base and the rate of growth/decay.
The larger the base (b > 1), the faster the growth. The smaller the base (0 < b < 1), the faster the decay.
Explain the significance of the y-intercept in an exponential function.
The y-intercept represents the initial value of the function when x = 0. It is the point where the function starts its growth or decay.
How does the domain of an exponential function influence its behavior?
Since the domain is all real numbers, the function is defined for all values of x, allowing it to model continuous growth or decay over time.
Explain the concept of concavity for exponential decay functions.
Exponential decay functions are concave up. This means that the rate of decay decreases as x increases, but the function never changes direction.
How to determine if a function represents exponential growth or decay?
Identify the base 'b' in the function . If b > 1, it's growth. If 0 < b < 1, it's decay.
How to find the y-intercept of an exponential function?
Set x = 0 in the function . The y-intercept is f(0) = a.
How to apply a vertical shift to an exponential function?
Add a constant 'k' to the function: . If k > 0, shift up. If k < 0, shift down.
How to find the limit of an exponential function as x approaches infinity?
If b > 1, the limit is infinity. If 0 < b < 1, the limit is 0.
How to model population growth with an exponential function?
Use the formula , where is the initial population, r is the growth rate, and t is the time.
How to solve for time in an exponential growth/decay problem?
Set up the equation . Use logarithms to solve for t:
How to determine the equation of an exponential function from two points?
- Substitute the points into to get two equations. 2. Solve for 'a' in one equation. 3. Substitute 'a' into the other equation and solve for 'b'. 4. Substitute 'a' and 'b' back into the general form.
How to determine the vertical shift given a graph of an exponential function?
Compare the horizontal asymptote of the transformed function with the horizontal asymptote of the original function (). The difference is the vertical shift.
How to solve for the growth/decay rate given two data points?
- Set up the equation , where and are the data points, and t is the time difference. 2. Solve for r:
How to find the initial value of an exponential function given a point and the base?
- Substitute the point (x, y) and the base 'b' into the general form . 2. Solve for 'a':