How to read a graph
Every point on the graph shows an input x along the bottom and the output y up the side. The line is the set of all such pairs for your function. Where it crosses the horizontal axis, y is zero, which is a solution of the equation. Where it crosses the vertical axis, x is zero, which is the starting value.
Move your pointer over the graph and the readout shows the exact value of each function at that x, with a dot on each curve. For an equation such as x^2 − 4 = 0, look for where the curve crosses the x-axis: that is x = −2 and x = 2.
Some shapes to try
A straight line such as 2x + 1 has a steady slope. A quadratic like x^2 − 3x + 2 makes a parabola that crosses the axis at x = 1 and x = 2. sin(x) is a wave that repeats every 2π, 1/x has two branches that never touch the axes, and e^x grows ever faster. Plot two together, such as x^2 and 2x + 3, and the points where they cross are the solutions of x^2 = 2x + 3, which are x = −1 and x = 3.
Tips and limits
Use brackets to be clear about what belongs together: write sin(x)/x, not sin x/x. The calculator draws one pixel at a time, so very sharp features or rapid oscillations at a large zoom-out may look rough. Zoom in to see them properly.
For solving a quadratic exactly, use the quadratic equation calculator, and for general calculations use the scientific calculator.
Questions people ask
How do I graph a function?
Type an expression using x into one of the boxes, for example x^2 - 4, sin(x) or 1/x. The graph appears as you type. Use the example buttons for common shapes, and Add function to plot up to four curves in different colours on the same axes.
What can I type in a function?
You can use + − × ÷, powers with ^ (x^3), brackets, implicit multiplication such as 2x or 3(x+1), the constants pi and e, and the functions sin, cos, tan, asin, acos, atan, ln, log (base 10), sqrt, cbrt, abs and exp. Writing y = at the start is optional.
How do I zoom and move the graph?
Drag with the mouse or one finger to pan. Scroll the wheel or pinch with two fingers to zoom around the pointer. The plus, minus and 1:1 buttons zoom in, zoom out and reset. With the graph focused, the arrow keys pan, plus and minus zoom and 0 resets.
Why is there a gap in my graph?
A function has no value at some points. 1/x is undefined at 0, ln(x) and sqrt(x) are undefined for negative numbers, and tan(x) is undefined at odd multiples of 90°. The calculator leaves a gap there instead of drawing a false line across the asymptote.
Should I use radians or degrees?
Pick radians for most maths and physics, since the standard shapes of sin(x) and cos(x) repeat every 2π (about 6.28). Choose degrees if your angles are in degrees, where they repeat every 360. The setting changes how the trig functions read x.