HP 40gs HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010.p - Page 64

The advantage of doing it this way is that if you zoom in or out by a factor of 2 or 4 or 5, the cursor jumps will stay at (relatively) nice values allowing you to trace more easily. In this case, the cursor now moves in jumps of 0.05, which is ideal for most purposes. If you are not interested in tracing along the graph then this may not be important. The disadvantage of this method is that you need to have at least some of the graph showing on the screen before you can zoom in or out to show more! Auto Scale can sometimes give you this first step. Composite functions The Function aplet is capable of dealing with composite functions such as f ( x + 2) or f ( g ( x)) in its SYMB view. The and keys are particularly helpful with this. For example, if we define F1(x) = x2 −1 and F 2(x) = x , then we can use these in our defining of F3(X), F4(X). See the screen shot on the left below. If the highlight is now positioned on each of these in turn, and the performed. The result is shown in the right hand snapshot. key pressed then the substitution is ( )2 Notice that the calculator is smart enough to realize in F3(X) that x − 1 is the same as x − 1 , although not, unfortunately, smart enough to keep track of the implications for the domain, which are that F3(X) should be defined only for non-negative x. There is a limit to this however. If you define F1(x) = x2 − x −1 and then F 2(x) = F1( x +1) , then the routine will not simplify ( x +1)2 − ( x +1) −1 to x2 + x −1 . 64