Here are the essential concepts you must grasp in order to answer the question correctly.
Differentiability
A function is differentiable at a point if it has a defined derivative at that point, meaning the function's graph has a tangent line that is well-defined. This requires the function to be continuous at that point and for the left-hand and right-hand derivatives to be equal. Points where the graph has sharp corners, vertical tangents, or discontinuities indicate non-differentiability.
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Continuity
A function is continuous at a point if the limit of the function as it approaches that point equals the function's value at that point. This means there are no breaks, jumps, or holes in the graph at that point. For a function to be continuous over an interval, it must be continuous at every point within that interval.
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Closed Interval
A closed interval, denoted as [a, b], includes all numbers between a and b, as well as the endpoints a and b themselves. In the context of calculus, analyzing functions over closed intervals is important for determining properties like continuity and differentiability at the endpoints, which can behave differently than points within the interval.
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Improper Integrals: Infinite Intervals