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f(x)={[-x^(2)+3x," if "x < 1],[2x+2," if "x >= 1]:}
evaluate the limit 
lim_(x rarr1)f(x). If the limit does not exist, write DNE.

f(x)={x2+3x if x<12x+2 if x1 f(x)=\left\{\begin{array}{cl} -x^{2}+3 x & \text { if } x<1 \\ 2 x+2 & \text { if } x \geq 1 \end{array}\right. \newlineevaluate the limit limx1f(x) \lim _{x \rightarrow 1} f(x) . If the limit does not exist, write DNE.

Full solution

Q. f(x)={x2+3x if x<12x+2 if x1 f(x)=\left\{\begin{array}{cl} -x^{2}+3 x & \text { if } x<1 \\ 2 x+2 & \text { if } x \geq 1 \end{array}\right. \newlineevaluate the limit limx1f(x) \lim _{x \rightarrow 1} f(x) . If the limit does not exist, write DNE.
  1. Approach 11 from Left: To evaluate the limit of a piecewise function as xx approaches a point, we need to consider the limit from both sides of that point. In this case, we need to find the limit of f(x)f(x) as xx approaches 11 from the left and from the right.
  2. Approach 11 from Right: First, let's find the limit as xx approaches 11 from the left, which means we will use the part of the function that applies when x<1x < 1: f(x)=x2+3xf(x) = -x^2 + 3x.\newlinelimx1f(x)=limx1(x2+3x)\lim_{x \to 1^-} f(x) = \lim_{x \to 1^-} (-x^2 + 3x)\newlineNow we substitute xx with 11.\newlinelimx1f(x)=(1)2+3(1)=1+3=2\lim_{x \to 1^-} f(x) = -(1)^2 + 3(1) = -1 + 3 = 2
  3. Comparison and Conclusion: Next, we find the limit as xx approaches 11 from the right, which means we will use the part of the function that applies when x1x \geq 1: f(x)=2x+2f(x) = 2x + 2.\newlinelimx1+f(x)=limx1+(2x+2)\lim_{x \to 1^+} f(x) = \lim_{x \to 1^+} (2x + 2)\newlineNow we substitute xx with 11.\newlinelimx1+f(x)=2(1)+2=2+2=4\lim_{x \to 1^+} f(x) = 2(1) + 2 = 2 + 2 = 4
  4. Comparison and Conclusion: Next, we find the limit as xx approaches 11 from the right, which means we will use the part of the function that applies when x1x \geq 1: f(x)=2x+2f(x) = 2x + 2.
    limx1+f(x)=limx1+(2x+2)\lim_{x \to 1^+} f(x) = \lim_{x \to 1^+} (2x + 2)
    Now we substitute xx with 11.
    limx1+f(x)=2(1)+2=2+2=4\lim_{x \to 1^+} f(x) = 2(1) + 2 = 2 + 2 = 4Now we compare the two one-sided limits. If they are equal, the limit exists and is equal to that value. If they are not equal, the limit does not exist (DNE).
    From the left, we found the limit to be 22. From the right, we found the limit to be 44. Since these two values are not equal, the limit as xx approaches 11 does not exist.

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