Question

(see pic) please help, and try to explain, I forgot how to do them

Answer 1

Answer:

  (D) I and II only

Step-by-step explanation:

A function has a limit at a point if the limit from the left and the limit from the right are the same value.

Here f(3) = 5, and the linear function defined for x ≤ 3 is continuous, so the left limit exists.

The function defined for x > 3, when evaluated at x = 3, also has a value of 5. That function, too, is continuous up to x = 3, so the right limit is defined.

The left and right limits at x=3 are y=5, so the limit exists. (Statement I is true.)

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The function f(x) is defined as 5 for x=3, so the limit exists and is the same as the function value at x=3. That means the function is continuous at x=3. (You can draw the graph through that point without lifting your pencil.) (Statement II is true.)

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The slope of f(x) for x < 3 is 1; the slope for x > 3 is 4. There is a discontinuity in the slope at x=3, so the function is not differentiable there. (Statement III is false.)

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The graph shows the function in red and its derivative in blue. You will notice there is a discontinuity (step change) at x=3.