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Math

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PROBLEM

Is the function f(x)f(x) continuous at x=1x=-1, where f(x)=x+2f(x)=|x+2| if x1x \neq -1 and f(1)=1f(-1)=-1?

STEP 1

Assumptions1. The function f(x)f(x) is defined as x+|x+| for all x1x \neq -1 and 1-1 for x=1x = -1.
. The value of cc is 1-1.
3. We are checking for continuity at x=cx = c.

STEP 2

A function f(x)f(x) is continuous at a point x=cx = c if the following three conditions are met1. f(c)f(c) is defined.
2. limxcf(x)\lim_{x \to c} f(x) exists.
. limxcf(x)=f(c)\lim_{x \to c} f(x) = f(c).
We will check each of these conditions.

STEP 3

First, we check if f(c)f(c) is defined. From the definition of the function, we know that f(1)=1f(-1) = -1.

STEP 4

Next, we need to calculate the limit of f(x)f(x) as xx approaches cc from both the left and the right. If both of these limits exist and are equal, then limxcf(x)\lim_{x \to c} f(x) exists.

STEP 5

We calculate the left-hand limit, which is limxcf(x)\lim_{x \to c^-} f(x).
limx1f(x)=limx1x+2\lim_{x \to -1^-} f(x) = \lim_{x \to -1^-} |x+2|

STEP 6

Since xx is approaching 1-1 from the left (i.e., x<1x < -1), the expression inside the absolute value, x+2x+2, is negative. Therefore, x+2=(x+2)|x+2| = -(x+2).
limx1f(x)=limx1(x+2)\lim_{x \to -1^-} f(x) = \lim_{x \to -1^-} -(x+2)

STEP 7

Now, we substitute x=1x = -1 into the expression to calculate the left-hand limit.
limx1f(x)=(1+2)=1\lim_{x \to -1^-} f(x) = -(-1+2) = -1

STEP 8

Next, we calculate the right-hand limit, which is limxc+f(x)\lim_{x \to c^+} f(x).
limx1+f(x)=limx1+x+2\lim_{x \to -1^+} f(x) = \lim_{x \to -1^+} |x+2|

STEP 9

Since xx is approaching - from the right (i.e., x>x > -), the expression inside the absolute value, x+2x+2, is positive. Therefore, x+2=x+2|x+2| = x+2.
limx+f(x)=limx+(x+2)\lim_{x \to -^+} f(x) = \lim_{x \to -^+} (x+2)

STEP 10

Now, we substitute x=x = - into the expression to calculate the right-hand limit.
limx+f(x)=+2=\lim_{x \to -^+} f(x) = -+2 =

STEP 11

Since the left-hand limit (-) and the right-hand limit ($$) are not equal, $\lim_{x \to c} f(x)$ does not exist.

SOLUTION

Therefore, the function f(x)f(x) is not continuous at x=c=x = c = -, because it does not meet all three conditions for continuity at that point.

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