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  1. AP Calculus
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What is an inverse function?

A function that 'reverses' another function. If f(a)=bf(a) = bf(a)=b, then f−1(b)=af^{-1}(b) = af−1(b)=a.

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What is an inverse function?

A function that 'reverses' another function. If f(a)=bf(a) = bf(a)=b, then f−1(b)=af^{-1}(b) = af−1(b)=a.

What does it mean for a function to be differentiable?

A function is differentiable at a point if its derivative exists at that point.

What is an invertible function?

A function that has an inverse function.

Define the derivative of a function.

The derivative of a function f(x)f(x)f(x) is a measure of how f(x)f(x)f(x) changes as xxx changes.

What is a tangent line?

A line that touches a curve at a point and has the same slope as the curve at that point.

What is the point-slope form of a line?

The equation of a line given a point (x1,y1)(x_1, y_1)(x1​,y1​) and slope mmm: y−y1=m(x−x1)y - y_1 = m(x - x_1)y−y1​=m(x−x1​).

What is the domain of a function?

The set of all possible input values (x-values) for which the function is defined.

What is the range of a function?

The set of all possible output values (y-values) of the function.

What does strictly increasing mean?

A function f(x)f(x)f(x) is strictly increasing if, for any x1<x2x_1 < x_2x1​<x2​, we have f(x1)<f(x2)f(x_1) < f(x_2)f(x1​)<f(x2​).

What is the reciprocal of a number?

The reciprocal of a number xxx is 1/x1/x1/x.

Explain the relationship between the derivatives of a function and its inverse.

The derivative of the inverse function at a point is the reciprocal of the derivative of the original function at the corresponding point. If f(a)=bf(a) = bf(a)=b, then (f−1)′(b)=1f′(a)(f^{-1})'(b) = \frac{1}{f'(a)}(f−1)′(b)=f′(a)1​.

How are the graphs of a function and its inverse related?

The graphs of a function and its inverse are reflections of each other across the line y=xy = xy=x.

What does the derivative of a function represent graphically?

The derivative of a function at a point represents the slope of the tangent line to the function's graph at that point.

Why is it important to know if a function is strictly increasing or decreasing when finding its inverse?

A strictly increasing or decreasing function is guaranteed to be one-to-one, and therefore invertible.

What is the significance of f′(f−1(x))f'(f^{-1}(x))f′(f−1(x)) in the inverse function derivative formula?

It represents the derivative of the original function evaluated at the inverse function, ensuring the correct corresponding point is used for the reciprocal calculation.

Explain the concept of local linearity.

At a sufficiently small scale, a differentiable function can be approximated by its tangent line.

What is the relationship between a function's domain and its inverse's range?

The domain of f(x)f(x)f(x) is the range of f−1(x)f^{-1}(x)f−1(x), and the range of f(x)f(x)f(x) is the domain of f−1(x)f^{-1}(x)f−1(x).

Explain the importance of differentiability when finding the derivative of an inverse function.

The original function must be differentiable at the point corresponding to the inverse function's input for the inverse derivative to exist.

What is the difference between f(x)f(x)f(x) and f−1(x)f^{-1}(x)f−1(x)?

f(x)f(x)f(x) is the original function, and f−1(x)f^{-1}(x)f−1(x) is its inverse, which 'undoes' the operation of f(x)f(x)f(x).

What is the difference between f′(x)f'(x)f′(x) and (f−1)′(x)(f^{-1})'(x)(f−1)′(x)?

f′(x)f'(x)f′(x) is the derivative of the original function, and (f−1)′(x)(f^{-1})'(x)(f−1)′(x) is the derivative of its inverse.

If the graph of f(x)f(x)f(x) is increasing, what does that tell you about the graph of (f−1)′(x)(f^{-1})'(x)(f−1)′(x)?

If f(x)f(x)f(x) is increasing, f′(x)>0f'(x) > 0f′(x)>0, so (f−1)′(x)>0(f^{-1})'(x) > 0(f−1)′(x)>0 as well, meaning the graph of (f−1)′(x)(f^{-1})'(x)(f−1)′(x) is positive.

How can you visually identify the inverse of a function on a graph?

The graph of the inverse function is the reflection of the original function across the line y=xy = xy=x.

What does a vertical tangent line on the graph of f(x)f(x)f(x) imply about the derivative of its inverse?

A vertical tangent line on f(x)f(x)f(x) means f′(x)=0f'(x) = 0f′(x)=0 at that point, which implies the derivative of the inverse function is undefined (has a vertical asymptote) at the corresponding point.

How does the concavity of f(x)f(x)f(x) relate to the graph of (f−1)′(x)(f^{-1})'(x)(f−1)′(x)?

The concavity of f(x)f(x)f(x) affects the rate of change of f′(x)f'(x)f′(x), which in turn affects the shape of (f−1)′(x)(f^{-1})'(x)(f−1)′(x). A concave up f(x)f(x)f(x) may lead to a different shape for (f−1)′(x)(f^{-1})'(x)(f−1)′(x) compared to a concave down f(x)f(x)f(x).

What does it mean if the graph of f(x)f(x)f(x) is symmetric about the origin?

It means f(x)f(x)f(x) is an odd function, i.e., f(−x)=−f(x)f(-x) = -f(x)f(−x)=−f(x).

What does the graph of f′(x)f'(x)f′(x) tell you about where f−1(x)f^{-1}(x)f−1(x) is increasing or decreasing?

If f′(x)>0f'(x) > 0f′(x)>0, then f(x)f(x)f(x) is increasing, and f−1(x)f^{-1}(x)f−1(x) is also increasing. If f′(x)<0f'(x) < 0f′(x)<0, then f(x)f(x)f(x) is decreasing, and f−1(x)f^{-1}(x)f−1(x) is also decreasing.

What does a sharp corner in the graph of f(x)f(x)f(x) imply about the differentiability of f−1(x)f^{-1}(x)f−1(x)?

A sharp corner in f(x)f(x)f(x) means it's not differentiable at that point, which can affect the differentiability of f−1(x)f^{-1}(x)f−1(x) at the corresponding point.

How can you visually determine the domain and range of f−1(x)f^{-1}(x)f−1(x) from the graph of f(x)f(x)f(x)?

The domain of f−1(x)f^{-1}(x)f−1(x) is the range of f(x)f(x)f(x), and the range of f−1(x)f^{-1}(x)f−1(x) is the domain of f(x)f(x)f(x).

What does a horizontal asymptote in f(x)f(x)f(x) tell you about f−1(x)f^{-1}(x)f−1(x)?

A horizontal asymptote in f(x)f(x)f(x) becomes a vertical asymptote in f−1(x)f^{-1}(x)f−1(x).

If f(x)f(x)f(x) is linear, what can you say about the graph of (f−1)′(x)(f^{-1})'(x)(f−1)′(x)?

If f(x)f(x)f(x) is linear, f′(x)f'(x)f′(x) is constant, so (f−1)′(x)(f^{-1})'(x)(f−1)′(x) is also constant.