Question

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determine the intervals for which f(x), graphed below, is continuous and differentiable.

a. continuous on \\((-5, -1) \cup (1, 4)\\); differentiable nowhere.
b. continuous on \\((-1, 1) \cup (4, 8)\\); differentiable nowhere.
c. continuous on \\((-5, 8)\\); differentiable on \\((-1, 1) \cup (4, 8)\\).
d. continuous on \\((-5, 8)\\); differentiable on \\((-5, -1) \cup (-1, 1) \cup (1, 4) \cup (4, 8)\\).

Explanation:

Analyze continuity of the function

The graph of \(f(x)\) is defined on the interval \((-5, 8)\). Looking at the graph, there are no breaks, holes, vertical asymptotes, or jumps. The curve is drawn in a single continuous stroke. Therefore, \(f(x)\) is continuous on the entire domain \((-5, 8)\).

Identify points of non-differentiability

A continuous function is not differentiable at sharp corners, cusps, or vertical tangents. Looking at the graph, there are sharp turns (corners) where the slope changes abruptly:

• At \(x = -1\), the graph transitions from a horizontal line to a line with a positive slope.
• At \(x = 1\), the graph transitions from a positive slope to a horizontal line.
• At \(x = 4\), the graph transitions from a horizontal line to a line with a negative slope.

Thus, \(f(x)\) is not differentiable at \(x = -1\), \(x = 1\), and \(x = 4\).

Determine intervals of differentiability

Since the function is continuous on \((-5, 8)\) but not differentiable at the corner points \(x = -1\), \(x = 1\), and \(x = 4\), we exclude these points from the domain of differentiability. This splits the domain into four open intervals:

• \((-5, -1)\)
• \((-1, 1)\)
• \((1, 4)\)
• \((4, 8)\)

Thus, \(f(x)\) is differentiable on \((-5, -1) \cup (-1, 1) \cup (1, 4) \cup (4, 8)\).

Match with the given options

Let's evaluate the options:

• Option A states continuous on \((-5, -1) \cup (1, 4)\), which is incorrect.
• Option B states continuous on \((-1, 1) \cup (4, 8)\), which is incorrect.
• Option C states differentiable on \((-1, 1) \cup (4, 8)\), which misses two intervals.
• Option D states continuous on \((-5, 8)\) and differentiable on \((-5, -1) \cup (-1, 1) \cup (1, 4) \cup (4, 8)\). This matches our findings perfectly.

Answer:

• A. Continuous on (-5, -1)\(\cup\)(1,4); differentiable nowhere.
• B. Continuous on (-1,1)\(\cup\)(4,8); differentiable nowhere.
• C. Continuous on (-5, 8); differentiable on (-1,1)\(\cup\)(4,8).
• D. Continuous on (-5, 8); differentiable on (-5, -1)\(\cup\)(-1,1)\(\cup\)(1,4)\(\cup\)(4,8). (Correct answer)