Always keep in mind that you can't turn your brain off
when the calculator is turned on. For any calculator result you need to ask
| Is this result reasonable? |
| Is it consistant with other results? |
| Can it be checked, preferable by some other method? |
| Could there be other answers also? |
Here are some other things to keep in mind, in no particular order:
1. Note that there is a difference between subtraction, "-", and a negative sign, " (-) ". These use different keys.
2. Use plenty of parentheses when entering expressions, more than
you would normally use when writing the expression by hand, so that the meaning
is unambiguous. Here are some examples.
3. If you are graphing a trig function and the graph does not show the expected
periodic shape but is apparently a straight line,
a. maybe your window
is badly chosen and you need to zoom out.
b. maybe you are
in degree mode when you should be in radian mode (or vice versa).
4. To get more quickly to menu options past choice 7, which don't show on
the initial screen, try pressing the up arrow instead of repeatedly pressing
the down arrow.
5. Hidden twists and turns in a graph can be very hard to find unless you know they are there. Don't assume that if your window shows an attractive graph you are seeing all the interesting features. Use calculus to find critical points and/or zoom out or in.
6. nDeriv(Y1,X,v) will give an incorrect answer if the function Y1 is not actually differentiable at the number v. This command is found on the Math menu and computes the (approximate) numerical value of the derivative Y1'(v), where X is the variable in the formula for Y1 and v is a specific value of X. Check for differentiability at v by examining the formulas for Y1 and its derivative, or, informally, check the graph of Y1 to be sure there is no break, vertical tangent, or corner at X=v.