Putting it All Together
5. Let's Get Our Hands Dirty
Alright, time to roll up our sleeves and put our newfound knowledge to the test! Let's tackle some example problems to solidify your understanding of continuity. Remember, the key is to systematically apply our three-step process.
Example 1: Consider the function f(x) = { x + 2, if x 1; 3x, if x > 1 }. Is this function continuous at x = 1? First, f(1) = 1 + 2 = 3 (defined!). Second, the left-hand limit as x approaches 1 is 1 + 2 = 3, and the right-hand limit as x approaches 1 is 3 1 = 3. Since the left-hand and right-hand limits are equal, the limit exists and is equal to 3. Third, the limit (3) equals f(1) (which is also 3). Therefore, the function is continuous at x = 1.
Example 2: Consider the function f(x) = (x + 3) / (x - 2). Is this function continuous at x = 2? First, f(2) is undefined (division by zero!). Therefore, the function is not continuous at x = 2. We didn't even need to bother checking the limit!
Example 3: Consider the function f(x) = { x^2, if x < 0; 1, if x = 0; 2x, if x > 0 }. Is this function continuous at x = 0? First, f(0) = 1 (defined!). Second, the left-hand limit as x approaches 0 is 0^2 = 0, and the right-hand limit as x approaches 0 is 2 0 = 0. Since the left-hand and right-hand limits are equal, the limit exists and is equal to 0. Third, the limit (0) does not equal f(0) (which is 1). Therefore, the function is not continuous at x = 0. This is a removable discontinuity!
Practice makes perfect! The more continuity questions you solve, the more comfortable you'll become with identifying potential discontinuities and applying the three-step process. Don't be afraid to make mistakes — that's how you learn! Grab some textbooks, search for practice problems online, and keep honing your skills.