CASIO fx-991CW

[lrdheat]

I like this calculator! I can define g(x) to be d/dx of f(x), create a table for both to find where extremums are nearby, then use the solver to find g(x)=0, save the solution into, say, A, go to calculate app, enter f(A) to find the extremum! I can find roots of f(x), save them into variables and then integrate from one saved variable to the next to find the area under the curve between roots. Another neat deal is that the calculator uses 17-22 internal digits meaning that the answer will come out to an actual fraction instead of a repeating decimal when the 991EX, or even the fx-CG50 will show the repeating decimal. When integrating an improper integral such as 1/sqrt(x-1) from 0 to 1, the 991EX allows a calculation when the upper end of the interval is 1-1*10^-12. The 991CW allows 1-1*10^-18 to be used, resulting in a much better approximation for such an integral. One needs to download the manual to understand how to access/enter functions, but it is easy, makes sense rather quickly. I like that f(x), g(x) is accessible in the calculate app. The stats app is good as well as the distribution app. Still much more to explore!