Ten Habits to Quit Before Calculus
In This Chapter
Recognizing all the bad habits
Remembering all the correct habits
You’ve come this far in math, for which you deserve high praise. But we can say with confidence that only 1 percent of you have few to no bad math habits. We wrote this chapter on breaking bad math habits in hopes that you’ll recognize a mistake that you commonly make and resolve to not make it anymore. The 1 percent of you who are perfect can now leave the building!
Operating Out of Order
Don’t fall for the trap that many students do by performing operations in order from left to right. For instance, 2 – 6 · 3 doesn’t become –4 · 3, or –12. You’ll reach those incorrect answers if you forget to do the multiplication first. Focus on following the order of PEMDAS every time, all the time:
Parentheses (and other grouping devices)
Multiplication and Division from left to right
Addition and Subtraction from left to right
Don’t ever go out of order, and that’s an order!
Squaring without FOILing
Always remember to FOIL. Here’s a common mistake we see: (x + 3)2 = x2 + 9. Why is that wrong? Because you forgot that to square something means to multiply it times itself. Foiled again! Here’s the correct process: (x + 3)2 = (x + 3)(x + 3). You should reach ...