Limit definition w/ graphs

Today's activity introduces mathematical "zooming".

1. Consider \(f(x) = \dfrac{2 x^2-x-6}{x-2}, x\neq2\) and notice \(\displaystyle\lim_{x \to 2} f(x) = 7\).

  1. If \(6 < f(x) < 8\), what domain makes \(f(x)\) go off the "sides" of the calculator window?
    What is the largest window you can make? Hint: Stay close to \(x = 2\).
  2. If \(6.9 < f(x) < 7.1\), what domain makes \(f(x)\) go off the "sides" of the calculator window? What is the largest window you can make?
  3. If \(6.99 < f(x) < 7.01\), what domain makes \(f(x)\) go off the "sides" of the calculator window? What is the largest window you can make?
  4. How can we find the "largest" domains above without guessing-and-checking?

2. Consider \(g(x) = \dfrac{x}{x-2}, x \neq 2\) and notice \(\displaystyle\lim_{x \to 1} g(x) = -1\).

  1. If \(-2 < g(x) < 0\), what domain makes \(g(x)\) go off the "sides" of the calculator window? What is the largest window you can make? Hint: Stay close to \(x=1\).
  2. If \(-1.1 < g(x) < -0.9\), what domain makes \(g(x)\) go off the "sides" of the calculator window? What is the largest window you can make?
  3. If \(-1.01 < g(x) < -0.99\), what domain makes \(g(x)\) go off the "sides" of the calculator window? What is the largest window you can make?
  4. For parts a-c, what are the largest windows that will work that are centered at \(x=1\)? For example, \([0,3]\) is not centered at \(x=1\), but \([0,2]\) is.