Graphing calculator

Typing a function

Write the right-hand side of y = …, using x for the variable: x^2 − 4, 2x + 1, sin(x), sqrt(x), abs(x), 1/x. A number next to x multiplies it, so 2x means 2 × x, and x^2 means x squared. The usual order applies: powers first, then × and ÷, then + and −. Use brackets when in doubt, as in (x + 1)/(x − 1). The keys on the scientific calculator list every name you can use.

Reading the graph

The view starts at −10 to 10 on both axes. Zoom in and out, or type the edges you want into the four boxes. The graph is drawn by working out y at every point across the screen. Where a function has a gap, such as 1/x at x = 0 or tan(x) at a right angle, the line is broken rather than joined across the gap.

Checking it

A picture can mislead, so the page also lists the points you would check by hand: where each curve crosses the y-axis, where it crosses the x-axis, and where the first two curves meet. Crossings are found by narrowing down between two x values where the sign changes, and are shown to six significant digits. The table of values below gives y for each x, at whatever step you choose, so you can plot the curve on paper and compare.

Limits

This is a function grapher for y in terms of x. It does not plot circles, inequalities or equations such as x² + y² = 25, and it does not do calculus.