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  1. AP Pre Calculus
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What is an exponential function?

A function of the form f(x)=abxf(x) = ab^xf(x)=abx, where a is the initial value, b is the base (b > 0, b ≠ 1), and x is the exponent.

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What is an exponential function?

A function of the form f(x)=abxf(x) = ab^xf(x)=abx, 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 b>1b > 1b>1. The function increases rapidly as x increases.

Define exponential decay.

Exponential decay occurs when 0<b<10 < b < 10<b<1. The function decreases rapidly as x increases.

What is the initial value in f(x)=abxf(x) = ab^xf(x)=abx?

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, (−∞,∞)(-\infty, \infty)(−∞,∞).

What is a vertical shift?

A transformation of the form g(x)=f(x)+kg(x) = f(x) + kg(x)=f(x)+k, which shifts the graph of f(x)f(x)f(x) 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 f(x)=abxf(x) = ab^xf(x)=abx?

'a' represents the initial amount or starting value of the exponential function at x = 0.

How to determine if a function represents exponential growth or decay?

Identify the base 'b' in the function f(x)=abxf(x) = ab^xf(x)=abx. 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 f(x)=abxf(x) = ab^xf(x)=abx. The y-intercept is f(0) = a.

How to apply a vertical shift to an exponential function?

Add a constant 'k' to the function: g(x)=f(x)+kg(x) = f(x) + kg(x)=f(x)+k. 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 P(t)=P0(1+r)tP(t) = P_0(1 + r)^tP(t)=P0​(1+r)t, where P0P_0P0​ 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 f(t)=abt=targetvaluef(t) = ab^t = target\\_valuef(t)=abt=targetv​alue. Use logarithms to solve for t: t=log⁡(targetvaluea)log⁡(b)t = \frac{\log(\frac{target\\_value}{a})}{\log(b)}t=log(b)log(atargetv​alue​)​

How to determine the equation of an exponential function from two points?

  1. Substitute the points into f(x)=abxf(x) = ab^xf(x)=abx 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 (y=0y=0y=0). The difference is the vertical shift.

How to solve for the growth/decay rate given two data points?

  1. Set up the equation y2=y1(1+r)ty_2 = y_1(1+r)^ty2​=y1​(1+r)t, where y1y_1y1​ and y2y_2y2​ are the data points, and t is the time difference. 2. Solve for r: r=(y2y1)1/t−1r = (\frac{y_2}{y_1})^{1/t} - 1r=(y1​y2​​)1/t−1

How to find the initial value of an exponential function given a point and the base?

  1. Substitute the point (x, y) and the base 'b' into the general form y=abxy = ab^xy=abx. 2. Solve for 'a': a=ybxa = \frac{y}{b^x}a=bxy​

What does the Exponential Growth Theorem state?

If a quantity increases at a rate proportional to its size, then it exhibits exponential growth.

What does the Exponential Decay Theorem state?

If a quantity decreases at a rate proportional to its size, then it exhibits exponential decay.

What does the Limit of Exponential Function Theorem state?

For b>1b > 1b>1, lim⁡x→∞bx=∞\lim_{x \to \infty} b^x = \inftylimx→∞​bx=∞ and lim⁡x→−∞bx=0\lim_{x \to -\infty} b^x = 0limx→−∞​bx=0. For 0<b<10 < b < 10<b<1, lim⁡x→∞bx=0\lim_{x \to \infty} b^x = 0limx→∞​bx=0 and lim⁡x→−∞bx=∞\lim_{x \to -\infty} b^x = \inftylimx→−∞​bx=∞.

What does the Vertical Shift Theorem state for exponential functions?

Adding a constant 'k' to an exponential function, f(x)=abx+kf(x) = ab^x + kf(x)=abx+k, shifts the graph vertically by 'k' units, changing the horizontal asymptote to y = k.

What does the theorem about the domain and range of exponential functions state?

The domain of f(x)=abxf(x) = ab^xf(x)=abx is all real numbers, and the range is (0,∞)(0, \infty)(0,∞) if a > 0, or (−∞,0)(-\infty, 0)(−∞,0) if a < 0, assuming no vertical shifts.

What does the theorem about the concavity of exponential functions state?

Exponential functions of the form f(x)=abxf(x) = ab^xf(x)=abx are always concave up if a > 0 and always concave down if a < 0.

What does the theorem about the y-intercept of an exponential function state?

The y-intercept of an exponential function f(x)=abxf(x) = ab^xf(x)=abx is always 'a', which is the value of the function when x = 0.

What does the theorem about horizontal asymptotes of exponential functions state?

For f(x)=abxf(x) = ab^xf(x)=abx, the horizontal asymptote is y = 0 if there are no vertical shifts. Vertical shifts will change the horizontal asymptote accordingly.

What does the theorem about the relationship between the base and growth/decay rate state?

If b > 1, the function exhibits exponential growth. If 0 < b < 1, the function exhibits exponential decay. The magnitude of 'b' influences the rate of growth or decay.

What does the theorem about transforming exponential functions state?

Transformations such as vertical shifts, reflections, and stretches/compressions can be applied to exponential functions, altering their position, orientation, and shape.