Chapter 20

Ten Things to Remember

This chapter contains ten things you should definitely remember. That’s not too much to ask, is it? If your mind is already crammed to capacity, you can make some room by first reading Chapter 21, “Ten Things to Forget.”

Your Sunglasses

If you’re going to have to study calculus, you might as well look good.

tip.eps If you wear sunglasses and a pocket protector, it’ll ruin the effect.

a2 - b2=(a-b)(a+b)

This factor pattern is quasi-ubiquitous and somewhat omnipresent; it’s used in a plethora of problems and forgetting it will cause a myriad of mistakes. In short, it’s huge. Don’t forget it.

9781118791295-eq1902.eps, but 9781118791295-eq1903.eps Is Undefined

9781118791295-eq1904.eps, and so 4 times 2 is 8. If 9781118791295-eq1905.eps had an answer, that answer times zero would have to equal 5. But that’s impossible, making 9781118791295-eq1906.eps undefined.

Anything0=1

The only exception is , which is undefined. The rule holds for everything else, including negatives and fractions. ...

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