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Pls help me do Calc corrections!

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(Based on todays review)

  • LammettHash

    1. a=2,b=3 makes it so that

    \displaystyle\lim_{x\to1^-}f(x)=\lim_{x\to1}(3-x)=2
    \displaystyle\lim_{x\to1^+}f(x)=\lim_{x\to1}(2x^2+3x)=5

    and because the one-sided limits do not agree, f(x) is not continuous at x=1 under these conditions.

    2. For f(x) to be continuous, we need both limits to match up; specifically, we require

    \displaystyle\lim_{x\to1}(ax^2+bx)=a+b=2

    3. Similar to (2), we need the limits from either side of x=2 to agree:

    \displaystyle\lim_{x\to2^+}f(x)=\lim_{x\to2}(5x-10)=0
    \implies\displaystyle\lim_{x\to2^-}f(x)=\lim_{x\to2}(ax^2+bx)=4a+2b=0\implies 2a+b=0

    4. f(x) will be continuous everywhere so long as a,b are chosen such that both a+b=2 and 2a+b=0.

    a+b=2\implies b=2-a\implies 2a+(2-a)=a+2=0\implies a=-2\implies b=4

    5. I'll leave this part to you.