DeltaCE 2.2

DeltaCE 2.2: the Δ key tells you what anything is, and word problems type in their own words.

The Δ key (prgm, on what you typed or on the last answer): what it is, in a textbook's words, the facts a textbook asks about it, and what to do next on 1 to 4.

• Functions: a quadratic's vertex, axis, minimum or maximum, range, discriminant, vertex form and factored form; a polynomial's degree and end behavior; a sinusoid's amplitude, period, phase shift, midline and range (from 2sin(3x-π)+1 as typed); exponential growth or decay with its factor and rate; then the domain, intercepts, symmetry, asymptotes and holes.
• Equations and inequalities: the kind, every solution (complex ones for a quadratic with none real, excluded values for a rational one); a trig equation's general solution and every solution in [0, 2π); an inequality's solution, its interval notation and a number line.
• Curves in x and y: a line's slope, intercepts, slope-intercept and standard forms; circles, ellipses, hyperbolas and parabolas by completing the squares: center, radius, vertices, foci, asymptotes, focus and directrix.
• Numbers, data, matrices, systems: prime or not, prime factors and divisors; a fraction's decimal, percent and mixed number; data's mean, median, mode, quartiles (the TI's way), standard deviations and outliers; a matrix's rank, determinant, inverse and eigenvalues; where two lines meet, or why they don't.
• Check your answer: type yours while the book's answer shows, then prgm: equal, equal but for a constant (two antiderivatives), or the x where they differ.
• A card takes 0.2 to 2 s on the calculator.

Word problems, in their words (more → Word problems, or a word typed in the search): 49 phrases with boxes, like "the value of [] when [] = []", "the average rate of change of [] from [] = [] to []", "[] at [] % compounded [] times a year for [] years". Also shapes' areas and volumes, sequences, simple and compound interest, working together, proportions, and a thrown ball (when it lands, how high it goes). Tell a story a fact a line ("[l] is [3] more than [2w]", "a rectangle [l] by [w] has perimeter [36]"), each one shown as its equation, then "find [w]": w = 5, l = 13. Nothing is stored in your variables.

The answer bar: under an answer, one row: ◀ ▶ flip it through its forms (F4 still does), then prgm with the moves it offers; on the card, More actions lists them all. Digits still start a new calculation, enter still shows the steps.

Also new: more → Things to do, a card of what DeltaCE does (and a first-start tour); menus open and close about twice as fast (from FlowCE, credited); floor, ceiling, norm, conjugate, nCr, products, log base b and nth derivatives drawn in their symbols; steps for powers typed with ^ or x².

Fixed: physical constants (_c_, _g_) now give their values, and compound SI units their names (9_J, 24_W); answers in textbook form (rationalized denominators, log for log₁₀, roots simplified, complex numbers as a+bi); x/0 no longer crashes ("undefined (a division by 0)"); systems and compound inequalities typed alone are solved; a limit like lim √(1+4/(9x^(2/3))) at 0 read past the end of a list; the antiderivative of 1/√(x⁴−16x²) had an undefined atan(i) in it; no more "≈ undef" under an answer; the analysis found period 2π for sin(3x) (it is 2π/3); keys lost while the battery was read. The catalog's ranm and ranv no longer promise random laws that this build ignores. Out: Practice (and its "Your turn" screen), binomial( and two random generators typed in the console (the Probability screen does them), and 105 commands found nowhere in DeltaCE (no menu, search or template): room for the Δ key.

Install: from the DeltaCE page in Chrome or Edge, or send DeltaCE.b84 with TI Connect CE. For the TI-84 Plus CE and TI-83 Premium CE on OS 5.3 to 5.8.4; installing erases the calculator's apps and archived files.