Find all the points of discontinuity of the function ff defined by f(x)={x+2, if x<10, if x=1x−2, if x>1f(x)=\left\{\begin{array}{rr} x+2, & \text { if } x<1 0, & \text { if } x=1 x-2, & \text { if } x>1 \end{array}\right.

Answer: The function f(x) is discontinuous at x=1x=1 .

Step-by-step solution

Step 1: Analyze continuity for x<1x < 1

For all values of x<1x < 1 , the function is defined as f(x)=x+2f(x) = x+2 . This is a polynomial function, and polynomial functions are continuous everywhere. Therefore, f(x) is continuous for all x<1x < 1 .

Step 2: Analyze continuity for x>1x > 1

For all values of x>1x > 1 , the function is defined as f(x)=x−2f(x) = x-2 . This is also a polynomial function, and thus it is continuous for all x>1x > 1 .

Step 3: Check continuity at x=1x = 1

To check for continuity at x=1x=1 , we need to evaluate the left-hand limit, the right-hand limit, and the function value at x=1x=1 . The left-hand limit is lim⁡x→1−(x+2)=3\lim_{x \to 1^-} (x+2) = 3 . The right-hand limit is lim⁡x→1+(x−2)=−1\lim_{x \to 1^+} (x-2) = -1 . The function value at x=1x=1 is given as f(1)=0f(1) = 0 .

Step 4: Determine discontinuity at x=1x = 1

Since the left-hand limit (3) is not equal to the right-hand limit (-1), the limit of the function as xx approaches 1 does not exist. For a function to be continuous at a point, the limit must exist and be equal to the function's value at that point. Therefore, the function is discontinuous at x=1x=1 .

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