173 quiz 2.4 – 2.6 solution

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Problem 1     Scratchwork at left. The solution begins "Let delta = 0.5," and must go all the way to "abs(sqr(x) – 3) < 0.1."

On the left, you see a sequence of calculations concluding that that delta must be smaller than 0.59; note that numbers in the range [0.59, 0.61) are too large. I chose 0.5 because it's certainly smaller than 0.59, and it's shorter, too: I like that.

The square roots of 8.5 and 9.5 are well within the bounds (2.9, 3.1).

Problem 2     I find that "plan B" on the right is a heck of a lot easier to understand. I wouldn't think of using the model on the left without a footnote...