What you can type
Equations like 2x + 3 = 7 or x^2 - 5x + 6 = 0. Inequalities like 3 - 2x < 9, or two at once like 1 < 2x + 3 ≤ 7. Systems: put each equation on its own line, or separate them with commas. Fractions and mixed numbers like 2 1/3 + 3/4. Expressions to expand, simplify and factor, like (x + 2)(x - 3). Functions like f(x) = x^2 - 4x + 3, to get the vertex, zeros and a graph.
How to write it
The box writes the way maths looks. Type ^ and what follows goes up as a power; type _ and it goes down, as in x_1. Type / and what came before goes over a line, with what follows under it. A plus, minus, equals or space steps back down from a power or out from under a line; to put a whole sum up there, wrap it in brackets: x^(y + 1) or (x + 1)/(x - 1). The arrow keys move in and out of each part too. Multiplication can be left out: 2x and 3(x + 1) both work. √ or sqrt( starts a square root, and | an absolute value.
Exact answers, then decimals
Answers stay exact wherever school maths would keep them exact: fractions stay fractions, and square roots are simplified, so x^2 = 50 gives x = ±5√2 rather than 7.0710678. The decimal is shown beside it. Equations that are not polynomials, like 2^x = 10 or sin x = 0.5, are solved numerically and the answers are marked with ≈.
The steps
Linear equations and inequalities show each move: collecting terms, then dividing, with the sign flipped when you divide by a negative. Quadratics are factored when they factor and solved with the quadratic formula when they do not, with the discriminant worked out. Fraction sums show the common denominator. Use the steps to check your own working rather than to skip it.
Questions
Can it show the graph?
Yes. Any expression or equation in one letter is graphed underneath, with its zeros, vertex and intercepts marked. Drag the graph to move it, and scroll or pinch to zoom. An equation in x and y, like y = 2x + 1 or a circle with a line, is drawn on the same axes.
Can it solve for a letter other than x?
Yes. When an equation has several letters, like A = 1/2 b h, a Solve for menu appears so you can pick which one to get on its own.
Does it do trigonometry in degrees?
Switch Degrees on before solving something like sin x = 0.5; the answers are then in degrees. Radians are the default, as in most maths beyond school.
What does the answer with an R mean?
When a number does not divide exactly, the answer is also shown as a whole number and a remainder: 50 ÷ 7 is 7 R 1, because 7 sevens are 49, with 1 left over.
Is it free?
Completely, with no sign-up and no limit. Everything is worked out in this page on your device, so nothing you type is sent anywhere.